Vegetable Udon Noodle Soup

By Drenda-Michell Brennan

The inspiration for this veggie udon noodle recipe is from a Japanese noodle dish called sukiyaki. Sukiyaki is traditionally made with marbled beef that is seared/cooked, in a cast iron pot over a fire or burner, directly in front of you.

In this Japanese udon recipe, I have taken the authentic signature ingredients of the sukiyaki sauce and made a warm flavorful udon dashi-based broth and added a variety of vegetables, noodles, and tofu that make it not only a healthy, whole food, and plant-based version, but also delicious! Check out our list of vegan Asian recipes for even more inspiration.

If you like to keep it super simple, with only about 15 minutes, you can even meal-prep these easy Asian Mason Jar Soups to have on hand for grab-and-go meals.

Ingredients you will need

Dashi Japanese soup broth– This is a key ingredient in many Japanese recipes, soups, and sauces that we use frequently, and you can easily make it at home using only 2 ingredients plus water. Be sure to try our miso ramen soup and somen cold noodle soup recipes that also use dashi. While you are making dashi, consider repurposing the dashi stock ingredients to make furikake rice seasoning.

Udon noodles– These are thick and white and have a glossy sheen when cooked.  They have a mild flavor and a chewy doughy texture and are made from only three ingredients- wheat, salt, and water. They taste amazing in soups and stir-fries. Try our udon noodle stir fry to see what I mean!

Glass Noodles– Also called harusame noodles. They are thin, transparent, gluten-free noodles made of potato or sweet potato starch. You can use these quick-cooking Japanese noodles in spring rolls, noodle salads, stir-fries, soups, and hot pot dishes. They are clear, silky-smooth, and have a delightful chewy texture.  Their neutral flavor soaks up broths, soups, and seasonings well.

Daikon This is a Japanese radish. It is a long white root vegetable with green leaves on top; it somewhat resembles a very large carrot. Daikon is widely used in Japanese cuisine and can be eaten raw, cooked, grated, and pickled. It has a crisp crunchy texture that becomes tender and juicy as it soaks up the flavors in sauces and soups when cooked.

Vegetables– Onions, mushrooms, cabbage, and bean sprouts are some of my favorite veggies to use in this soup. Feel free to customize the portions and varieties of vegetable ingredients to suit your personal preferences.

Soy curls– Used as a vegan meat substitute, soy curls are made from only one ingredient–non-GMO soybeans. There is nothing else added to them during processing–no salt or preservatives–and nothing is taken away from the whole bean. They can be purchased online and in some grocery stores. We have lots of soy curl recipes for you to try.

Sake – The alcohol in sake evaporates but leaves a distinct and important flavor.

Why use sake?

Sake is a Japanese wine made from fermented rice. A lot of traditional Japanese soup broths include a combination of soy sauce and sake because they blend well together and create an almost magical complexity to the broth. The alcohol evaporates from the broth as it cooks and only the distinct sake flavor is left.

What are udon noodles?

Udon noodles make up an important part of Japanese cuisine. Unlike the more readily known soba noodles, udon noodles are thicker and white, and have a glossy sheen when cooked.  They have a mild flavor and a chewy doughy texture and are made from only three ingredients- wheat, salt, and water. The best quality I saved for last, they taste amazing in soups and stir-fries!

We don’t easily find fresh Japanese udon noodles where we live, on the East Coast, but most Asian grocers carry them in both frozen and dried aisles. They can also be frequently found at health food stores and even ordered online for your udon soup recipes.

How to make vegetable udon noodle soup

The recipe card at the bottom of the page has the full list of ingredients with measurements and instructions.

Step #1:  Prep Work– You’ll want to make your kombu dashi ahead of time. Dashi can be stored in the fridge for up to 14 days or frozen for up to three months. If you need to make it the day of, do it at least 2-3 hours beforehand for best results.

Step #2: Rehydrate the soy curls in vegetable broth for 10 minutes and cut into 2” strips.

Step #3: Prepare Ingredients– Drain, and slice all of the vegetables so they will be ready to add as soon as the soup base is ready. Slicing the veggies into strips or squares aids in eating with chopsticks.

Step #4: Boil the daikon disks in the kombu dashi soup base in a stock pot for 10 minutes to soften them before adding the rest of the ingredients.

Step #4: Once the daikon is soft enough to pierce with a fork, begin adding the rest of our ingredients to the stockpot in the following order. First, add the sake to the broth to allow time for the alcohol to evaporate.

Step #5: Next, add the soy sauce and half of the sugar and stir until the sugar is completely dissolved.

Step #4: Start adding the onions, mushrooms, udon noodles, napa, soy curls, green onions, glass noodles, and tofu. I layer them in this order to protect the more fragile ingredients from overcooking and crumbling from the weight of the other ingredients.

Step #5: Once all the ingredients are in the pot, sprinkle the remaining sugar over the top, cover, and simmer over medium-high heat for an additional 10 minutes.

Step #6: Add the sprouts about two minutes before cutting off the heat. They are tender and will only take a second to steam.

Step #7: When the glass noodles are clear and soft and all the ingredients have simmered in the soup base enough to absorb all the wonderful flavors, it’s time to eat! Serve in individual bowls with chopsticks (or forks) and a soup spoon. This dish is best served hot.  You can refrigerate leftovers for up the three days.

Pro tips and suggestions

In this recipe, I like to slice the daikon first because it will need to cook the longest. If you don’t need the entire daikon root, cut it in half and use the top portion, the part with the leaves attached, first.  Removing the leaves (that absorb moisture) extends the shelf life of the daikon radish.  Wrap the unused portion of daikon tightly in plastic wrap and store it in the fridge for future use. Slice off the top (the leafy part) and peel the section you will be using with a vegetable peeler, just like you would a carrot, and then slice into ¼” circular disks. 

If you’re using a new full head of napa cabbage, instead of slicing the strips horizontally from top to bottom, first slice it long-wise, splitting it straight down the middle. This way you will have two complete halves, one for now and one for your next meal. You can see the texture of napa cabbage changes from leafy near the top to crunchy as you work your way down and this way you get to experience all the textures with each meal. The photo above shows what I mean.

If you want to meal prep and make this an easy weeknight meal, you can make the sukiyaki udon sauce ahead and store it in an airtight container in the refrigerator. Prepare your toppings (veggies and tofu) a day ahead and store them in a separate covered container until you are ready for them. When you are ready to make this recipe, just pour the broth into the stock pot over the vegetables and noodles when you are ready to cook and serve them.

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