This Umami-Rich Sesame Soba Noodle Soup

Japanese cuisine is known for its noodles, and it’s probably the most likely place you’ll find soba. The buckwheat noodle is different from udon or even ramen in a pretty noticeable way: The defining characteristic of the noodle is its main ingredient, buckwheat. Buckwheat is an ancient grain also known as a pseudocereal, a seed that begins as a wheat-like grain that can then be ground into flour. The flour is then used to make the soba noodle (among other things), a popular gluten-free type of noodle that can be served hot or cold. Actually, it’s probably the noodle you’re most likely to see served cold, the earthy, slurpable long strands pairing well with salad dressings and fresh vegetables.

Soba noodles are equally in good in hot dishes, too, and because of their silkiness, they work well in delicate soups like this one written with developer Michelle McGlinn. Inspired by classic miso soup, this light and easy dashi broth is seasoned with nutty sesame and soy before being poured over tender-firm brown noodles. The soup is the perfect base for tofu and bok choy and makes an excellent side dish to flavorful sushi and sashimi dishes. Thanks to instant Hondashi, it also comes together in about 30 minutes, making it an excellent weeknight cup of warmth for when instant ramen just isn’t quite enough.

First, you’ll need a firm block of tofu, which you’ll need to drain and press before adding to the soup. Firm tofu will combine with the soup without losing shape or texture, but for a softer chew, you can also use soft tofu. From there, you’ll need baby bok choy, scallions, water, soy sauce, mirin, and sesame oil. The last two ingredients are the most important but also likely the hardest to find: Soba noodles and instant dashi. 

Instant dashi is available in Asian-specific markets and can also be bought online. The most common brand is Hondashi, but any brand will work. Dashi can also be made from scratch with kelp and bonito flakes, which are smoked and fermented tuna flakes — which means dashi is not typically vegetarian. To make this dish vegetarian, seek out vegetarian instant dashi (or make it yourself), which is usually made with kelp and mushrooms for a similar umami flavor. As for soba noodles, look in the noodle aisle for a brown, spaghetti-like pasta, usually sold tied together in 3-ounce bundles.

Drain the tofu and place it between several layers of paper towels, or between a thick kitchen towel. Place on a rimmed plate and press down with a heavy object, such as a skillet. Press for 30 minutes.

In the meantime, bring a pot of water to boil.

Add the soba noodles and cook until just barely al dente, about 2 ½ to 3 minutes.

Drain the soba noodles and rinse with warm water to remove the starches.

Divide the soba noodles into bowls.

To make the broth, add 8 cups water and instant dashi to a pot. Bring to a simmer.

Season the broth with soy sauce, mirin, and sesame oil.

Dice the drained and pressed tofu into 1-inch squares.

Add the tofu and bok choy to the broth and cook until the bok choy is bright green and soft, about 5 minutes.

Ladle the broth, tofu, and bok choy over the noodles.

Top with scallions to serve.

With many pasta-based soups, it’s common to cook the pasta directly in the broth — good examples are Italian wedding soup, chicken noodle soup, and minestrone. It’s not always done this way, though: Delicate noodles like ramen, soba, and pho’s vermicelli are all made separately from the soup and divided into serving bowls before the broth is added. Besides preserving the texture of the noodles, this method also prevents leftover soup from becoming inedible with mushy, broken noodle strands and starchy broth. The question is, if you plan to eat soba noodle soup in one sitting, can you save yourself the extra pot and cook it all together?

The short answer is no. Soba noodles need to be rinsed of their starches before being added to soups and salads, or you’ll end up with clumpy, gummy noodles and cloudy, starchy broth. To prevent the noodles from becoming cold, they are often dunked into simmering hot water again before being divided into bowls, though rinsing with warm water will do the trick. If you want to streamline the process by cooking the soba noodles in the broth, you can, but be sure to dunk the noodles in right before serving to avoid overcooking, which will result in mushy noodles.

If you can’t find bok choy but want a similar green, you can add spinach for a close comparison or chard for something a little more chewy. You can also change up the tofu — though there’s nothing quite like the tender blocks of soy, you can replicate the texture with large white beans or lentils, or swap for chewy mushrooms. If you’re swapping for mushrooms, we recommend adding extra umami to the dish by browning the mushrooms first, before the water is added, so that the mushrooms are deeply savory and golden brown.

Besides mushrooms, you can add a plethora of vegetables to this soup to fill it with nutrients. With most veggies, plan to add them to the broth at the same time as the tofu — this goes for baby corn, broccoli, water chestnuts, napa cabbage, peas, and zucchini. Other vegetables may benefit from being browned slightly beforehand, like carrots, onions, peppers, and garlic. When browning, you can leave the veggies in the pot while making the dashi to streamline the process and fully soften the vegetables.