Authentic Kongguksu Recipe (Korean Cold Soy Milk Noodles)

Kongguksu (콩국수) is a traditional Korean summer noodle dish made with thin wheat noodles served in a cold, creamy broth of freshly cooked and blended soybeans.

Unlike bibim naengmyeon or spicy makguksu, kongguksu contains no red chili sauce. Its appeal comes from the pure, nutty flavor of soybeans, a silky but substantial broth, and the refreshing contrast of cold noodles and crisp cucumber.

A traditional bowl may be seasoned with little more than salt. Sesame seeds, pine nuts, cucumber, tomato, and boiled egg are popular additions, but the soybean broth should always remain the star.

Prep Time: 20 minutes
Bean Soaking Time: 6–8 hours or overnight
Cook Time: 25 minutes
Chilling Time: 1–2 hours
Total Active Time: About 45 minutes
Servings: 4

1. What Is Kongguksu?

Kong (콩) means beans or soybeans, while guksu (국수) means noodles.

Kongguksu is therefore a Korean noodle dish served in a cold soybean broth.

The traditional broth is made by soaking dried soybeans, cooking them until tender, and blending them with cold water until smooth and creamy.

The broth is not dairy milk and does not require cream.

Its rich texture comes naturally from finely ground soybeans.

A typical bowl contains:

• Thin wheat noodles such as somyeon
• Cold homemade soybean broth
• Julienned cucumber
• Sesame seeds
• Optional tomato
• Optional boiled egg
• Salt for seasoning

Unlike many Korean noodle dishes, authentic kongguksu is usually mild and non-spicy.

2. Korean Kitchen Note

Kongguksu is strongly associated with the hottest months of the Korean summer.

The combination of chilled broth and noodles makes it refreshing, while soybeans give the dish much more richness and body than a simple cold noodle soup.

One of the interesting things about kongguksu is how little seasoning it needs.

Good soybean broth should taste naturally nutty, creamy, and slightly sweet from the beans themselves.

Traditionally, many Koreans season their bowl simply with salt.

There is also a famous regional debate in Korea about whether kongguksu should be seasoned with salt or sugar.

Salt is particularly common in Seoul and many central regions, while adding sugar is more familiar in some southern areas and individual households.

There is no need to season the entire pot heavily. Serve the broth relatively plain and let each person adjust their own bowl.

3. Ingredients

For 4 servings:

For the Soybean Broth

• 1 cup dried yellow soybeans
• 5–6 cups cold water, divided
• 3 tablespoons toasted sesame seeds
• 2 tablespoons pine nuts, optional
• 1–1 1/2 teaspoons salt, plus more to taste

For the Noodles

• 400 g (about 14 oz) somyeon or thin Korean wheat noodles

For the Toppings

• 1/2 English cucumber, julienned
• 1 medium tomato, cut into wedges, optional
• 2 hard-boiled eggs, halved, optional
• 1 tablespoon toasted sesame seeds

For Serving

• Ice cubes, optional
• Additional salt
• Sugar, optional according to preference
• Kimchi

4. Global Ingredient Substitution Guide

Dried Soybeans

Use plain dried yellow soybeans rather than roasted soybeans or sweetened soy products.

They are widely available in Korean and Asian supermarkets and many health-food stores.

Organic dried soybeans work equally well.

Black Soybeans

Kongguksu can also be made with Korean black soybeans such as seoritae.

The resulting broth may have a pale gray-green or darker color and a slightly different natural sweetness.

Somyeon

Somyeon are thin Korean wheat noodles that cook quickly and work beautifully in cold noodle dishes.

Japanese somen is an excellent substitute.

Thin wheat noodles are preferable to chewy naengmyeon noodles because kongguksu traditionally has a softer, more delicate noodle texture.

Pine Nuts

Pine nuts create additional richness but are not essential.

You can omit them and increase the sesame seeds slightly.

Store-Bought Soy Milk

Unsweetened soy milk can be used for a very quick version, but it does not taste exactly like freshly blended Korean soybean broth.

A practical shortcut is to blend unsweetened soy milk with a small amount of cooked soybeans, toasted sesame seeds, or nuts to create more body and nuttiness.

Avoid vanilla-flavored or sweetened soy milk.

5. Step-by-Step: How to Make Kongguksu

Step 1. Soak the Soybeans

Rinse the dried soybeans thoroughly.

Place them in a large bowl and cover with plenty of cold water.

Soak for approximately 6 to 8 hours or overnight.

The beans will expand considerably as they absorb water.

Step 2. Cook the Soybeans

Drain the soaked beans and place them in a medium pot.

Add enough fresh water to cover them generously.

Bring to a boil over medium-high heat.

Reduce the heat and cook until the soybeans are tender but not falling apart.

Depending on the beans and soaking time, this generally takes approximately 15 to 20 minutes.

Step 3. Cool the Beans

Drain the cooked soybeans, reserving a little cooking liquid if desired.

Cool the beans until comfortable to handle.

If you want an especially smooth and pale broth, gently rub the soybeans between your hands in cold water and remove as many loose skins as possible.

This step is optional.

Step 4. Blend the Soybean Broth

Place the cooked soybeans in a high-speed blender.

Add toasted sesame seeds, optional pine nuts, and approximately 4 cups of very cold water.

Blend on high speed for 1 to 2 minutes or until exceptionally smooth.

Step 5. Adjust the Thickness

Check the consistency.

The broth should be creamy and substantial enough to coat the noodles lightly, but it should still pour easily.

Add additional cold water gradually until you reach your preferred consistency.

Step 6. Season Lightly

Add approximately 1 teaspoon of salt.

Blend briefly again.

Keep the seasoning deliberately mild because each diner can add more salt at the table.

Step 7. Chill the Soybean Broth

Transfer the broth to a covered container.

Refrigerate for at least 1 to 2 hours until thoroughly chilled.

If the broth separates slightly while standing, simply stir before serving.

Step 8. Prepare the Toppings

Julienne the cucumber.

Cut the tomato into wedges and halve the boiled eggs if using.

Keep all toppings refrigerated until serving.

Step 9. Cook the Noodles

Bring a large pot of water to a strong boil.

Add the somyeon noodles.

Cook according to package directions, usually approximately 3 to 4 minutes.

Stir occasionally so the strands do not stick together.

Step 10. Rinse the Noodles

Drain immediately.

Rinse thoroughly under cold running water while gently rubbing the noodles between your hands.

This removes excess surface starch and stops the cooking process.

Step 11. Chill and Drain

Give the noodles a final rinse in ice-cold water.

Drain extremely well.

Divide the noodles among four chilled serving bowls.

Step 12. Add the Soybean Broth and Serve

Stir the chilled soybean broth thoroughly and pour it generously around the noodles.

Top with cucumber, tomato, boiled egg, and sesame seeds.

Add several ice cubes if desired.

Serve immediately with salt—and optional sugar—at the table so each diner can adjust the seasoning.

6. Korean Cook's Tips

Do not undercook the soybeans. Beans that remain too firm will produce a grainy broth.

Do not dramatically overcook them either. Excessively cooked soybeans can develop a heavier cooked-bean flavor.

Use a powerful blender if possible. The finer the soybean particles become, the creamier the finished broth feels.

Remove soybean skins for an extra-smooth broth. This is optional but creates a more refined texture.

Keep the broth thick. Kongguksu should not resemble watery soy milk.

Chill everything. Broth, noodles, toppings, and serving bowls should all be cold.

Season after tasting. The natural soybean flavor should remain prominent.

7. Nutrition Notes

Soybeans are a notable source of plant protein and also provide fat, dietary fiber, and several vitamins and minerals.

Unlike many noodle soups in which the broth contributes relatively little protein, kongguksu broth is made from the whole soybean rather than simply flavored water.

The noodles provide most of the carbohydrate in the meal.

Sesame seeds and optional pine nuts add additional fats, protein, minerals, and nutty flavor.

Cucumber and tomato contribute fresh vegetables and additional texture.

The amount of sodium can remain relatively modest if the soybean broth is seasoned lightly and additional salt is added only according to individual taste.

8. Why It Works: Cooking Science

Why Does Kongguksu Become Creamy Without Dairy?

Soybeans contain substantial amounts of protein and fat.

When cooked soybeans are blended very finely with water, these components become dispersed throughout the liquid.

The fine soybean particles, proteins, and oils create a thick, creamy texture even though no milk or cream is added.

Why Do Soaked Soybeans Cook Faster?

Dried soybeans contain relatively little water.

During soaking, water gradually enters the bean structure and hydrates it.

This reduces the amount of hydration that must occur during cooking and helps the beans cook more evenly.

Why Does a Powerful Blender Matter?

Perceived creaminess depends partly on particle size.

Large soybean particles produce a coarse or grainy sensation.

Breaking those particles into much smaller pieces creates a smoother and more homogeneous broth.

Why Add Sesame Seeds or Pine Nuts?

Seeds and nuts contain oils that contribute richness and aroma.

When blended into the soybean broth, their fat becomes dispersed throughout the liquid, enhancing the creamy mouthfeel and roasted nutty flavor.

Why Rinse the Noodles in Cold Water?

Boiling releases starch onto the noodle surface.

Cold-water rinsing removes loose starch, stops residual cooking, and prevents the noodles from clumping.

For a cold noodle dish, this step also rapidly brings the noodles to serving temperature.

9. What to Serve With Kongguksu

Kongguksu has an extremely mild and nutty flavor, so a strongly seasoned Korean side dish provides excellent contrast.

Serve it with:

• Baechu kimchi – Napa cabbage kimchi
• Yeolmu kimchi – Young radish kimchi
• Oi kimchi – Cucumber kimchi
• Geotjeori – Fresh kimchi
• Gamja Jeon – Korean potato pancakes
• Bindaetteok – Korean mung bean pancakes

Spicy and slightly sour kimchi is especially good because it cuts through the creamy soybean broth.

10. Frequently Asked Questions

What is kongguksu?

Kongguksu is a Korean summer noodle dish made with wheat noodles served in a cold, creamy broth of cooked and finely blended soybeans.

Is kongguksu made with soy milk?

Traditional kongguksu broth is essentially fresh homemade soybean milk or soybean puree made specifically for the dish by blending cooked soybeans with water.

Is kongguksu vegan?

The basic combination of soybeans, water, noodles, cucumber, and sesame can be vegan if the noodles and other ingredients meet vegan requirements. Simply omit the egg.

Is kongguksu gluten-free?

Traditional somyeon noodles contain wheat and therefore are not gluten-free.

The soybean broth itself can be gluten-free, and gluten-free noodles may be substituted.

Should I add salt or sugar to kongguksu?

Both preferences exist in Korea. Salt is extremely common, while some regions and households enjoy adding sugar. The best approach is to keep the main broth lightly seasoned and let each diner adjust their own bowl.

Can I make kongguksu with store-bought soy milk?

Yes, for a quick version. Use plain unsweetened soy milk and blend it with toasted sesame seeds or cooked soybeans for a thicker, more traditional-style texture.

Why is my kongguksu broth grainy?

The soybeans may not have been cooked until fully tender, or the mixture may not have been blended long enough.

Removing the soybean skins and using a high-speed blender can make the broth smoother.

Why is my soybean broth too thin?

Too much water was probably added during blending.

Blend in additional cooked soybeans, sesame seeds, or pine nuts to restore body.

Can I make the soybean broth ahead?

Yes. Refrigerate it in an airtight container and use it within about 24 hours for the freshest flavor.

Stir well before serving because natural separation can occur.

Can I freeze kongguksu broth?

Freezing is possible, but the texture can change slightly after thawing.

For the smoothest broth, freshly made or refrigerated soybean broth is preferable.

What is black soybean kongguksu?

Black soybean kongguksu is made with black soybeans such as Korean seoritae instead of ordinary yellow soybeans. It has a darker color and its own slightly sweet, nutty character.

11. More Korean Recipes

If you enjoy refreshing Korean noodle dishes, try these recipes next:

• Makguksu – Korean Buckwheat Noodles
• Mul Naengmyeon – Korean Cold Noodle Soup
• Bibim Naengmyeon – Korean Spicy Cold Noodles
• Kalguksu – Korean Knife-Cut Noodle Soup
• Janchi Guksu – Korean Noodle Soup
• Sujebi – Korean Hand-Torn Noodle Soup

12. Key Takeaways

Authentic kongguksu is defined by thin wheat noodles served in a thick, chilled broth made from freshly cooked and finely blended soybeans.

The soybean broth should taste naturally nutty and creamy rather than heavily seasoned.

For the smoothest texture, soak the beans thoroughly, cook them until tender, blend them very finely with cold water, and add toasted sesame seeds or pine nuts for extra richness.

Rinse the cooked noodles thoroughly in cold water, drain them well, and serve everything intensely chilled with cucumber and sesame seeds.

Whether you prefer a pinch of salt or a little sugar, kongguksu is one of Korea's simplest and most refreshing ways to enjoy soybeans during the summer.