Step 1

Combine wakame and 2 Tbsp. water in a small bowl. Let sit, stirring occasionally, until softened, 25–30 minutes.

Step 2

Bring dashi to a simmer in a small saucepan. Add tofu and wakame and return to a very gentle simmer. Remove from heat. Submerge a fine-mesh sieve into liquid, add miso to sieve, and stir until miso dissolves.

Step 3

Divide among bowls and serve topped with scallion.