Bolder than your average miso soup, this version, inspired by one made at the Brooklyn restaurant Ganso Yaki, achieves its rich flavor with a robust dashi and blend of both dark and mild miso. Consider using hatcho miso for the dark one—it's a dense, heartier style made strictly with soybeans (as opposed to both rice and soybeans).
- 1 tablespoon (3g) dried wakame seaweed
- 1/2 ounce dried kombu (14g; about one 6- by 5-inch piece), rinsed in cold water
- Cold water
- 1/2 ounce katsuobushi (dried bonito shavings) (14g; about 2 1/2 cups)
- About 1/3 cake (160g) silken tofu, cut into 1/2-inch pieces
- 1 tablespoon (16g) mild miso, such as shiro (white) miso (see note above)
- 2 tablespoons (32g) dark miso, such as hatcho or aka (red) miso (see note above)
- 1 scallion, white and light green parts only, sliced thinly on the bias
In a small bowl, cover wakame with enough cold water to cover and let stand at room temperature until soft, about 15 minutes.
Meanwhile, in a medium saucepan, combine kombu with 3 1/2 cups (830ml) cold water and cook over medium heat until water just starts to boil, about 6 minutes. Remove kombu with tongs and discard or reserve for another use. (Kombu can be cut into thin slivers and tossed into a salad.)
Add a few tablespoons cold water to saucepan to lower temperature, then add katsuobushi and bring to a boil over high heat. Reduce heat and simmer dashi for 7 minutes.
Strain dashi through a fine-mesh strainer set over a heatproof bowl; discard katsuobushi. Return dashi to a clean saucepan. Drain wakame and add to dashi along with tofu; be very gentle, since tofu is fragile and will break easily. Set over medium heat until warmed through.
In a small bowl, whisk both misos with just enough warm dashi to dissolve into a thin paste. Remove dashi from heat and very gently stir in miso paste, being careful not to break the tofu.
Carefully ladle soup into warmed bowls, garnish with scallions, and serve immediately.