Japanese Soup: A Simple Miso Soup Recipe

Japanese miso soup is a savory broth made with dashi, miso paste, and simple additions such as tofu, seaweed, and scallions. This home-style version uses kombu and bonito flakes for a clear, aromatic stock; it comes together quickly, and the ingredients can be adjusted to suit different tastes and diets.

Ingredients

4 cups (950 ml) cold water
1 piece dried kombu, about 4 by 4 inches (10 by 10 cm; about 8 g)
1 cup (about 10 g) loosely packed katsuobushi, or dried bonito flakes
1 tablespoon (3 g) dried wakame seaweed
7 ounces (200 g) soft or medium-firm tofu, cut into ½-inch (1.25 cm) cubes
3 tablespoons (about 54 g) white or yellow miso paste, plus more to taste
2 scallions, thinly sliced (about ¼ cup or 25 g)

Instructions

Prepare the wakame and other ingredients. Put the dried wakame in a small bowl and cover it with cool water. Let it soak for 5 minutes, until pliable, then drain and gently squeeze out excess water. Cut it into bite-size pieces if the strands are long. While it soaks, cube the tofu and slice the scallions. Wakame expands considerably, so the measured dry tablespoon is enough for this batch.
Start the dashi. Wipe the kombu with a damp cloth to remove any grit; a light white powder on the surface is natural and contributes flavor, so do not scrub it away. Add the water and kombu to a medium saucepan. Set the pan over medium heat and warm it gradually for about 6 to 8 minutes, watching closely. Just before the water reaches a boil, when small bubbles gather around the edges, lift out the kombu with tongs. Avoid boiling the kombu, which can make the broth slimy or overly strong.
Steep and strain the bonito. Bring the liquid just to a boil, turn off the heat, and add the bonito flakes. Let them steep undisturbed for 2 minutes, until they have mostly sunk. Pour the broth through a fine-mesh strainer into a heatproof bowl or back into the saucepan. Do not press the flakes; squeezing them can make the dashi cloudy or bitter. Discard the used flakes, or save them for another use if you have a suitable recipe.
Warm the tofu and seaweed. Return the strained dashi to the saucepan over low heat. Add the tofu and drained wakame, then warm gently for 2 to 3 minutes. Keep the broth below a rolling boil so the tofu stays intact and the seaweed retains a pleasant texture. The tofu is already ready to eat; this step is simply to heat it through.
Dissolve the miso off the boil. Put the miso in a small bowl and ladle in about ½ cup (120 ml) of hot broth. Stir until smooth, then pour this mixture back into the saucepan. Stir gently and taste. Add another teaspoon of miso at a time if you want a saltier, fuller broth. Turn off the heat once the miso is incorporated; boiling after adding miso dulls its delicate aroma.
Finish and serve. Divide the soup among four small bowls and scatter the sliced scallions over the top. Serve promptly while hot. If the soup sits briefly before serving, give it a gentle stir so the miso, which can settle, is evenly distributed.

Tips

Use miso gradually. Miso varies in saltiness and intensity by type and brand. Start with 3 tablespoons, taste after dissolving it, and adjust in small amounts. If the broth becomes too salty, add a splash of hot water or unsalted dashi rather than trying to balance it with sugar.
Keep miso out of a hard boil. Add it after the tofu is warmed and the heat is off or very low. This keeps the soup fragrant and prevents the broth from turning cloudy. Reheating later is fine; just warm it gently rather than boiling it vigorously.
Choose tofu for the texture you like. Soft tofu gives the soup a delicate, custardy bite, while medium-firm cubes are easier to handle and hold their shape better. Patting tofu dry is optional; it can reduce excess water, but it is not necessary for this soup.
Know your dashi options. Kombu and katsuobushi are sold at Japanese or other Asian grocery stores and online. For a faster version, use instant dashi according to its package directions, checking whether it already contains salt or bonito. For a vegetarian substitute, steep kombu with a few dried shiitake mushrooms; the broth will be earthier and less smoky than bonito dashi.

Serving Suggestions

Serve miso soup as part of a Japanese-style meal alongside steamed rice, grilled fish, or a bowl of noodles. It also pairs well with tamagoyaki, lightly dressed greens, or small vegetable sides such as cucumber salad. A modest bowl is usually enough as a first course, while a larger serving with extra tofu and vegetables can work as a light lunch.

For a balanced bowl, ladle in both broth and solids rather than serving mostly liquid. Add scallions at the table if you want them to stay crisp. A small pinch of toasted sesame seeds can add a nutty note, though it is not essential and will change the traditional, clean flavor slightly. Keep salty accompaniments in mind: miso soup is already seasoned, so taste before adding soy sauce or other salty toppings.

Variations

Make it vegetarian or vegan: Replace the bonito dashi with kombu-and-shiitake broth. Soak 2 dried shiitake mushrooms (about 10 g) with the kombu in the measured water for at least 20 minutes, or refrigerate them in the water overnight; remove the kombu before it boils and simmer the mushrooms until tender. Slice the mushrooms and return them to the soup if you like. Check the miso label, since most miso is plant-based but ingredients can vary.

Change the miso: White miso tends to taste mild and a little sweet; yellow miso is more savory and robust. Red miso is generally stronger and saltier, so begin with less—about 2 tablespoons (36 g)—then adjust to taste. Blending two kinds is also an easy way to create a more layered broth. The exact salt level depends on the particular miso, so tasting matters more than following a fixed adjustment.

Add seasonal vegetables: Thinly sliced mushrooms, spinach, napa cabbage, daikon, or small cubes of winter squash can be added, but give firm vegetables enough time to become tender in the dashi before adding tofu and miso. Leafy greens need only a minute or two. Keep the additions moderate so the soup remains a broth with a few fillings rather than turning into a thick stew.

Use a different topping: Try thinly sliced mushrooms, blanched spinach, or a few cooked clams in place of some tofu. For clams or other seafood, cook them separately or in the broth until they open and are cooked through, then add miso off the heat. Tofu, wakame, and scallion remain the simplest combination and let the dashi flavor come through clearly.

Storage and Reheating

For food safety, refrigerate leftover soup within 2 hours of cooking. Transfer it to a covered, shallow container so it cools promptly, and keep it refrigerated for 3 to 4 days. The tofu and wakame may soften as they sit, and the miso flavor can become a little less bright, but the soup is still practical to reheat within that window. If you expect leftovers, reserve some sliced scallions separately and add them fresh when serving.

Reheat only the portion you plan to eat in a small saucepan over medium-low heat, stirring occasionally. Heat leftovers to 165°F (74°C), checking with a food thermometer, then take the pan off the heat; avoid a prolonged boil, which can break up tofu and flatten the miso’s aroma. A microwave also works: use a microwave-safe bowl, cover it loosely, stir during heating, and check the temperature in more than one spot. Do not leave soup at room temperature for extended periods. Freeze soup only if necessary; thawed tofu often becomes spongy, so freezing can noticeably change the texture.

Frequently Asked Questions

Can I use instant dashi instead of making it from scratch?
Yes. Follow the package directions to make about 4 cups (950 ml) of dashi, then continue with the tofu, wakame, and miso steps. Instant dashi is convenient and consistent, though its flavor may be saltier or more concentrated than homemade stock. Taste before adding the full amount of miso, especially if the dashi mix is seasoned.

What kind of miso is best for this soup?
White or yellow miso makes a gentle, familiar everyday soup, which is why either works well in this recipe. Red miso brings a deeper, more assertive flavor. There are many regional and household versions of miso soup in Japan, and there is no single required miso or filling; choose a paste you enjoy and adjust the amount to its saltiness.

Do I have to soak dried wakame first?
Soaking makes dried wakame easier to portion and helps it soften evenly. Five minutes in cool water is enough for the small amount in this recipe. Drain it before adding it to the broth, since the soaking water can carry a strong seaweed flavor. If your package gives different preparation instructions, follow those directions.

Why should I remove the kombu before the water boils?
Kombu releases useful flavor as it warms, but a hard boil can draw out compounds that make dashi slippery or overly pungent. Lift it out when small bubbles appear and the water is steaming. If you miss the moment and it briefly boils, the soup is not ruined; remove the kombu and continue, but aim for a gentler extraction next time.

Can I prepare the soup ahead?
You can make the dashi and cut the toppings ahead, then refrigerate them separately in covered containers. For the freshest flavor, warm the dashi with the tofu and wakame and dissolve in the miso just before serving. Fully prepared soup can also be refrigerated and reheated within 3 to 4 days, although its texture and aroma will be best when freshly made.

Is miso soup supposed to be salty?
It should be savory, but it should not taste harshly salty. Dashi provides a light, clear base, while miso supplies seasoning and depth. Miso pastes differ, and the saltiness of instant dashi varies too, so begin with the recipe amount, taste, and adjust. If you oversalt it, dilute with a little unsalted dashi or hot water rather than adding more ingredients that also contain salt.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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