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Hearty Soybean Soup with Natto

This soup is a flavorful combination of various soybean products, including natto, fermented soybeans. Here, the sticky texture of the natto is reduced a bit when sautéed; despite its aroma during preparation, neither its smell nor taste overpowers the soup, making this an appealing dish even for those who are not fans of natto.

(per serving)

Ingredients (Serves 3-4)

  • 8 green onions, 40 g / 1.5 oz. total
  • 2 t vegetable oil
  • 2 packs natto, each 40 g / 1.5 oz.; set aside Japanese mustard packets, if included
  • 1 t mustard (preferably Dijon), or more to taste
  • 600 ml (2 1/2 C) bouillon*1
  • 1 stem fresh thyme, or 2 pinches powdered thyme
  • 1 bay leaf
  • 150 g (1/3 lb.) tofu, firm or soft, drained, cut into 1 cm (1/2 in.) cubes
  • 200 ml (5/6 C) soy milk
  • 1 + 1/2 t Kikkoman Soy Sauce, or more to taste
  • Black pepper to taste
Optional garnish
  • Chopped green onion leaves
  • Chopped parsley
  • 1/2 piece abura-age*2, deep-fried tofu
  • Kikkoman Soy Sauce
  • *1 C (U.S. cup) = approx. 240 ml; 1 T = 15 ml; 1 t = 5 ml


  1. 1

    Separate the hollow green leaves from the solid part of the onion. Finely chop the solid part for use in the soup; then cut up a few of the hollow green leaves to set aside for optional garnish.

  2. 2

    Heat vegetable oil in a heavy-bottomed pan. Add natto and sauté over low heat, stirring lightly to prevent burning. Add the chopped onion and sauté until soft.

  3. 3

    Stir in pre-packaged Japanese mustard from the natto along with the mustard.

  4. 4

    Add the bouillon to the sautéed natto. Wrap thyme and bay leaf together in cheesecloth or pack into a bundle, and add to the pot. Bring to a boil; lower heat and simmer for 2-3 minutes.

  5. 5

    Add the diced tofu; after it rises to the surface, add the soy milk and 1 t soy sauce, then heat to just under the boiling point.

  6. 6

    Taste and depending on preference, add another 1/2 t soy sauce or more and sprinkle with black pepper.

  7. 7

    Serve in individual bowls garnished with chopped green onion leaves, parsley and/or abura-age, depending on preference. Serve hot.

  1. *1Either meat- or vegetable-based bouillon cubes or powder may be used. Use about 3/4 the amount of bouillon suggested in directions for a mild soup base.
  2. *2Preheat a non-stick frying pan. Over low heat, lightly brown both sides of the abura-age, pressing it down. Remove pan from heat, brush tofu with soy sauce. Cut in half and slice into 5 mm (1/4 in.) strips.

Recipe by Michiko Yamamoto

Vol. 28

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