Seaweed Soup Recipe

Prepare kombu stock

Rinse the kombu quickly under cold water to remove any grit. In a large pot, combine the 2 cups water and the kombu. Let soak for 10 minutes, then place over medium heat. Just before the water reaches a simmer (small bubbles forming around the edges), remove the kombu and discard or reserve for another use. This gentle infusion yields a mild kelp flavor.

Add stock and umami

Add the 6 cups of chicken or vegetable stock to the pot with the kombu-infused water. Bring to a gentle simmer. If using bonito flakes, add them now, simmer 2 minutes, then strain the broth through a fine sieve and discard the flakes. Return the strained broth to the pot.

Season the broth with 2 tablespoons soy sauce, 1 teaspoon salt, and 1/2 teaspoon pepper. Taste and adjust seasoning; reduce salt if you used salty stock. Keep the broth at a gentle simmer while you prepare the rest of the ingredients.

Rehydrate wakame

Place the 1 cup dried wakame in a bowl and cover with cool water. Let soak 5–10 minutes until expanded and tender. Drain, squeeze gently to remove excess water, and roughly chop if pieces are large (wakame expands significantly).

Prepare vegetables

While wakame soaks, thinly slice mushrooms, mince garlic, and slice ginger. Trim and thinly slice the scallions, reserving some green tops for garnish. If using spinach or baby bok choy, roughly chop leaves.

Add mushrooms, garlic, and ginger to the simmering broth. Simmer 4–6 minutes until mushrooms are tender and aromatics are fragrant. Add the rehydrated wakame and optional spinach or bok choy; simmer 1–2 minutes just until greens wilt but remain bright.

If adding tofu, gently slide the cubed tofu into the pot and simmer 2–3 minutes to heat through. If using cooked shrimp or shredded chicken, add them in the last 1–2 minutes just to warm (avoid overcooking shrimp). Stir gently to avoid breaking the tofu.

Turn off heat. Stir in 1 teaspoon sesame oil and 1/2 teaspoon rice vinegar or a squeeze of lemon if using, to brighten the flavors. Adjust seasoning with additional soy sauce or salt if needed.

Ladle soup into bowls. Garnish with sliced scallion tops, a sprinkle of toasted sesame seeds, and a pinch of red pepper flakes or shichimi togarashi if desired. Serve immediately.