Ingredients
5 cups water
3/4 ounce kombu (four 5-inch pieces)
1/3 cup bonito flakes
2 tablespoons soy sauce, plus more for seasoning
1 pound kabocha or buttercup squash, peeled and cut into 1-inch pieces
3 1/2 ounces White Beech (Bunapi), enoki, or shiitake mushrooms, trimmed
8 ounces soba noodles, preferably 100 percent buckwheat
Silken tofu (optional), for serving
Thinly sliced scallions, for garnish
Preparation
Bring water and kombu to a boil in a large saucepan. Remove from heat, stir in bonito flakes, and let stand 5 minutes. Pour broth through a fine sieve into a bowl, discard solids, and return broth to pan.
Add soy sauce, squash, and mushrooms to broth. Bring to a boil over high heat, reduce heat, and simmer, stirring occasionally, until squash is tender, about 10 minutes. Season with more soy sauce if desired.
Bring a large pot of water to a boil. Add noodles, and cook, stirring occasionally, until noodles are al dente, 5 to 7 minutes. Drain, and rinse under cold water.
Divide noodles among 4 bowls. Ladle soup over noodles, dollop with tofu, and garnish with scallions.
