Zaru Soba Recipe: Cold Buckwheat Noodles with Homemade Tsuyu

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18 min read

Last updated November 3, 2026

Last updated November 3, 2026: Full refresh and a correction that matters. Earlier versions of this recipe, going back to 2014, called soba noodles gluten free in the title. Most soba is not: the classic noodle is 80 percent buckwheat and 20 percent wheat, many supermarket brands are mostly wheat, and regular soy sauce in the dipping sauce contains wheat too. This edition fixes the title and the claim, explains exactly which soba is gluten free and how to build a gluten free version safely, merges my 2014 zaru soba recipe into this one (the old address now forwards here), adds the noodle cooking and rinsing steps the originals skipped, and replaces every unverifiable shopping link.

You know it is summer when you hear the loud cacophony of cicadas and slurp your soba, at least you do if you live in Japan. We in the U.S. know the sounds of cicadas well, but many people are missing out if they have never eaten soba noodles. I hope you will give it a try. This zaru soba recipe is extremely easy to make once you gather the ingredients. Japanese soba noodles are low in calories, nutritious, and best of all delicious. Just do not believe anyone who tells you they are automatically gluten free. That part takes one careful minute at the store, and it is the first thing below.

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How do you like your soba?

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How do you like your soba?

Cold zaru style, dipped in tsuyuHot, in a bowl of brothWith the spicy peanut sauceI have never tried it, but I am about to

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First, the Correction: Soba Is Not Automatically Gluten Free

Buckwheat is not wheat. It is the seed of a plant related to rhubarb, and it contains no gluten at all. The problem is the noodle. Pure buckwheat dough barely holds together, so noodle makers add wheat flour as a binder. The classic ratio even has a name, nihachi, two eight: 80 percent buckwheat flour to 20 percent wheat flour. Cheaper supermarket soba often goes much further; wheat flour is the first ingredient on many packages, which means the noodle is mostly wheat wearing a buckwheat costume. My old versions of this recipe waved at the label and moved on. For someone with celiac disease or a real wheat allergy, that is not good enough, so here is the whole picture.

The three kinds of soba you will actually meet

Then there is the sauce. Regular soy sauce is brewed from soybeans and wheat, so it is not gluten free, and bottled tsuyu and mentsuyu are built on soy sauce, so assume they contain wheat unless the label says otherwise. The swap is tamari, the Japanese sauce traditionally made with little or no wheat: choose one that is labeled gluten free, because not every tamari is wheat free. That label has legal meaning in the U.S.: under the FDA rule it means no wheat ingredient and under 20 parts per million of gluten.

How to make this recipe gluten free, honestly

• Buy juwari soba, 100 percent buckwheat, ideally labeled gluten free. If the package just says soba, assume it contains wheat.
• Build the tsuyu with tamari labeled gluten free in place of the soy sauce, in the same amount.
• Boil the noodles in fresh water that has not cooked wheat noodles, and rinse them the same way as below.
• Read the wasabi and furikake labels too. Seasoning blends vary.
• One separate warning: buckwheat itself is an allergen for some people, uncommon in the U.S. but well known in Japan and Korea. Gluten free does not mean allergen free.

If gluten is not your problem, buy nihachi and enjoy the better texture. Either way, read the ingredient list in order. That one habit is the difference between eating soba and eating brown wheat noodles.

Japanese Food in the U.S. Is Rarely Japanese at All

While I lived in Japan, soba, buckwheat noodles with a delicious dipping sauce and a few toppings, was one of my absolute favorite dishes. It is delicious year round but especially popular in the summer heat, since it is eaten cold.

Most Americans have very little knowledge of Japanese food beyond sushi, tempura, and teriyaki sauce. Unfortunately, most Japanese restaurants in the U.S. do not taste like any food I ever ate in my many years of living in Japan. I do not even recognize most of the items in Japanese restaurants here as remotely Japanese at all. Too many of them are run by people cashing in on the Japanese food craze without ever having trained in a Japanese kitchen, and it shows in every bite: wrong ingredients, improperly prepared, and outrageously overpriced. Japanese cuisine is as far removed from Korean and Chinese cuisine as you can possibly get. It is no more similar than German food is to Mexican food.

My Japanese friends who have visited here and tried our local restaurants were shocked. They thought the food was Chinese and completely unrecognizable. Imagine trying to get authentic Southern food in India and you will understand the point. Instead of paying through the nose for awful imitation food, cook it yourself at home. It will likely be much more delicious and certainly cheaper. That is why this recipe exists, and why I spell out where to find the ingredients for people who do not live near a big Japanese grocery store.

If you try this recipe and do not like it, do yourself a favor and give it at least one or two more tries. I did not care for it at first, because it has a very unique flavor. But now I love it to the point that I am a soba addict. A cup of cooked noodles has only about 113 calories, more with sauce and seasoning but not much more, and the noodles bring protein, fiber, and B vitamins along with the flavor. There are many ways to eat soba, hot and cold. This recipe is for the cold classic, zaru soba.

Ingredients for Zaru Soba

This can be the trickiest part. If you have an Asian grocer with a large Japanese section, you may be fine. Some of the ingredients you might need to order online. Plan on about 3.5 ounces (100 g) of dried soba per person.

1. Soba noodles. See the choosing section right below. The two honest picks, one gluten free and one not, are both there with links.
2. Tsuyu, the dipping sauce. You can buy it premade in a bottle, but that gets pricey very quickly and is not as good as making your own. The homemade recipe is below, and it is far more delicious and much cheaper. If you just want to try soba for the very first time, buy the sauce premade once. Then learn to make your own.
3. Green onions or fresh chives, chopped. You sprinkle these on the sauce or the noodles. Optional, but I love them, so I use them liberally.
4. Wasabi. You can buy this in pretty much any grocery store now. Buy an authentic Japanese brand; S&B is the one I named in 2014 and it is still the easy find. Wasabi not made in Japan has an odd taste. Stick to Japanese wasabi.
5. Shredded nori. This is simply the dried seaweed used on sushi. You probably cannot find it already shredded, but it is perfectly fine to buy sushi sheets and cut them into very small shreds yourself. The sheets are sold at any supermarket.
6. Roasted sesame seeds (optional but recommended). Purely my personal preference. I love toasted sesame seeds, so I usually sprinkle some on my soba. Available at any grocery store; I bought a large plastic jar for less than $2 at my local Kroger.
7. Salmon furikake (optional but recommended). Furikake is usually used on rice as a flavoring. It is a combination of ingredients that can include shredded seaweed, dried fish flakes, wasabi, sugar, salt, and many other combinations. You can use it instead of shredded nori alone, or in addition to the nori. Salmon furikake on Amazon
8. Shiso leaves (optional). Shiso is part of the mint family, and I love it. You will likely not be able to find fresh leaves anywhere, but you can order seeds and grow your own plants and eat them year round. Fresh is the way to go; chop a leaf over your soba for a really authentic kick. My guide to growing shiso explains how easy it is.
9. Grated daikon radish (optional). A large white Japanese radish you can sometimes find in the supermarket. I am not a big daikon fan, but I did not want to leave it out for people who enjoy that taste.

Choosing Your Soba Noodles

Two picks, labeled as plainly as I can manage, because this is exactly where the old version of this article misled people.

King Soba Organic 100 Percent Buckwheat Noodles (3 pack): the gluten free pick. The ingredient list is two items long, organic buckwheat flour and water, and the noodles are certified organic and gluten free. This is juwari, so treat it gently: it cooks fast and breaks more easily than blended soba, which is the honest price of 100 percent buckwheat.

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Hakubaku Organic Soba: the easy to find pick, and not gluten free. Its label reads wheat flour first, about 69 percent wheat to 29 percent buckwheat on the Australian data sheet, which makes it a wheat first blend. It is a decent, widely sold noodle for people who eat wheat, and it is also Exhibit A for why you read labels: the package says soba in big letters and wheat in small ones.

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Homemade Tsuyu Sauce

Important note: this recipe makes a concentrated solution. Keep it in an airtight container in the fridge for a few weeks. To eat it with soba, dilute it with about 2 or 3 parts cold water to 1 part concentrate. Otherwise the flavor will be far too strong. This makes enough tsuyu for many servings.

Tsuyu ingredients

• 1 cup soy sauce (or tamari labeled gluten free, for the gluten free version)
• 1 cup plus 2 tablespoons mirin
• 3/4 cup sake (any sake is fine; most grocery stores and any liquor store should have some cheap sake)
• 1 cup bonito flakes (katsuobushi)
• 1 piece of kombu, about 2×2 inches

Tsuyu instructions

In a medium saucepan, add only the sake at first and bring it to a boil. Then add the mirin and soy sauce and stir well. Then add the kombu and bonito flakes. Bring it to a boil and stir well, then reduce to low heat and cook for about 5 minutes, stirring occasionally; an extra few minutes is also fine. Turn off the heat and let it cool. Pour the mixture through a fine sieve or strainer. That is tsuyu sauce. Make sure no solid material is in the sauce, so strain well, then chill it.

Do not throw away the kombu or bonito. Set them aside and you can use them to make delicious homemade furikake to go over rice.

If you want to watch the dish come together before you cook, this is the video both of my old versions of this recipe pointed to:

How to Cook and Chill the Noodles

The original recipe told you to follow the package and left it at that. The package times are fine, but the method around them is the recipe, and zaru soba lives or dies on the rinse.

1. Bring a large pot of water to a rolling boil. Use plenty of water, and do not add salt. Soba is not pasta.
2. Fan the dried noodles out into the pot so the strands separate, and stir occasionally so they do not stick. Cook according to the package, typically about 4 to 5 minutes for dried soba, until just tender with a slight chew. Do not overcook; juwari especially goes soft and breaks.
3. Before you drain, you can save a cup or so of the hot cooking water. That is sobayu, and there is a use for it at the end of the meal, below.
4. Drain the noodles into a sieve and rinse them under cold running water, rubbing them gently with your hands to wash off the excess starch. Do not skip this. Unrinsed soba clumps and turns slimy.
5. Move the noodles to a bowl of ice water for about 30 seconds to chill them through and firm them up, then drain very well.
6. Arrange the noodles in neat mounds on a bamboo zaru tray if you have one, or on plates, and top with the shredded nori.

How to Eat Zaru Soba

This is just the way I prefer to eat it. I mix the wasabi and chopped green onions into my cup of diluted tsuyu. I sprinkle my soba with sesame seeds and furikake. Then you take your chopsticks, pick up a portion of noodles, dip it into the sauce, and do your best to soak it thoroughly and get some green onions on your portion. Hold the cup close to your mouth and slurp it in so as not to spill it everywhere. Not very elegant, but very practical and fun. Soba and slurping go hand in hand; in Japan the slurp is good manners, not bad ones.

When the noodles are gone, there is one last step most Americans never hear about. Pour some of the warm sobayu you saved into your remaining tsuyu and drink it like a soup. It is how a soba meal ends in Japan, and it is better than it sounds.

Before you eat, say ITADAKIMASU (ee-tah-dah-key-mas). It means simply “let’s eat,” said with a little gratitude built in. And after you finish, you say GOCHISOOSAMA (go-chee-so-sama), that was delicious. I certainly hope you think it is as delicious as I do and become a soba addict. (If the sounds and spellings of Japanese interest you, my description of the Japanese writing system is the deep end of that pool.)

Thai Peanut Soba Sauce

A few people wrote me asking about other sauces besides tsuyu. Yes, there are many. Here is a Thai and Japanese fusion sauce you can adjust to your tastes. Readers of my 2014 recipe will recognize its roots; this is the precise version, with the amounts written down.

For the spicy peanut sauce

• 5 tablespoons peanut butter
• 5 tablespoons water
• 5 tablespoons soy sauce, or tamari for gluten free
• 2 tablespoons sesame oil (optional, for flavor)
• 2 tablespoons honey
• Juice of 1 lime
• 1 clove garlic
• 1/4 cup chili sauce like sriracha (more or less depending on spice tolerance)
• 1/2 cup peanuts

Puree the sauce ingredients in a food processor or blender. Add the peanuts last so you can control how chunky it is; I like to leave it a little more on the chunky side. A little heat helps the flavors marry, so you can warm the mixed sauce in a pan for a few minutes and then chill it, or simply mix it very well and serve it as is. Personally I like a sauce that hits sweet, salty, sour, and spicy all at once, but you know your tastes better than anyone.

Make it a meal

If you want to make this more substantial, add chicken (grilled, boiled, baked, however you prefer), chopped up and added to the sauce, then pour it all over the noodles. Fish, pork, and beef also work; my personal favorite is a nice portion of pork tenderloin. Just do not season the meat too heavily, since the sauce is already doing that job. Vegetables go in just as easily: minced fresh garlic, chopped green onion, yellow squash or zucchini wedges, chopped cilantro, thinly sliced carrot, thinly sliced cucumber, boiled and cooled bean sprouts, shiitake mushrooms, steamed or boiled asparagus, and snow peas are all fair game. Use your judgment on whether each one is better cooked or raw.

Also try my Japanese corn on the cob, yaki tomorokoshi, which is the other Japanese recipe I make all summer.

Watchdog Approved

Winston’s Pick: Winston can’t use chopsticks, but he fully approves of the slurping. It’s the authentic way.

King Soba Organic 100 Percent Buckwheat Noodles, 3 Pack
The gluten free pick: organic buckwheat flour and water, nothing else. Juwari, the real thing.

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KeQiu 28 oz Ceramic Ramen/Noodle Bowl Set
Wide, deep bowls made to be held close to your mouth while you slurp, the proper technique.

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Antner Reusable Bamboo Chopsticks, 5 Pairs
Naturally textured bamboo that grips slippery soba far better than smooth lacquered sticks.

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Frequently Asked Questions

Is soba gluten free?

Usually, no. Buckwheat contains no gluten, but most soba noodles include wheat flour as a binder, the classic nihachi ratio is 20 percent wheat, and many supermarket brands are wheat first. Only juwari soba, 100 percent buckwheat, is made without wheat, and a fully gluten free serving also needs a gluten free sauce (tamari labeled gluten free instead of regular soy sauce), fresh cooking water, and a label check for cross contact. If a package does not say 100 percent buckwheat, assume it contains wheat.

Why do you rinse soba noodles after boiling?

To wash off the surface starch. Unrinsed soba clumps together and turns slimy, and the cold rinse plus a short ice water chill is what gives zaru soba its clean, firm bite. The rinse is not optional garnish work; it is half the dish.

Can I just buy the tsuyu instead of making it?

Yes, and for a first try that is a sensible shortcut. Bottled tsuyu and mentsuyu are sold as concentrates, so dilute them as the bottle directs, usually in the same 2 or 3 parts water to 1 part sauce neighborhood. Two cautions: bottled sauce gets pricey fast if soba becomes a habit, and regular bottled tsuyu is built on soy sauce, so it contains wheat unless it is labeled gluten free.

How long does homemade tsuyu concentrate keep?

A few weeks in an airtight container in the refrigerator, as this recipe has always said. It is mostly soy sauce, mirin, and sake, all sturdy ingredients. If it smells off, throw it out and make a fresh batch; it takes about ten minutes.

What is sobayu, and do I have to drink it?

Sobayu is the hot water the noodles cooked in, cloudy with buckwheat starch. At the end of the meal you pour a little into your leftover tsuyu and drink the mixture like a thin soup. You do not have to, but it is the traditional finish, it wastes nothing, and it tastes better than it sounds.

Sources

• Made in Japan: Japanese soba, usually not gluten free, and why (juwari and nihachi ratios, wheat as binder, cross contact)
• Chef JA Cooks: Types of soba noodles (juwari 100 percent, nihachi 80/20)
• FDA: Gluten and food labeling (what a gluten free claim must mean: no wheat ingredient, under 20 parts per million of gluten)
• Eden Foods: Soba, 100 percent buckwheat (buckwheat is naturally gluten free; made in a wheat and gluten free facility)
• Kikkoman: Zaru soba (chilled buckwheat noodles) (rinse and rub the noodles under cold water to remove sliminess)
• USDA nutrition data for Japanese soba noodles, cooked: 113 calories per cup (114 g), as reproduced at Medindia’s USDA based nutrition table.

So here is my question for you. Soba is the rare dish that tastes better the plainer it is: cold noodles, strong sauce, nothing fried, nothing drowned in cheese. Does that simplicity appeal to you, or does a bowl of noodles with almost nothing on it sound like a meal that forgot to happen? Tell me in the comments, and if you make it, tell me which sauce won at your house, tsuyu or peanut.