To make the dashi, combine water and kombu in a large pot. Bring to a boil. Remove from heat and discard kombu.

Stir in bonito flakes and cover pot. Let steep for 5 minutes. Strain out bonito flakes.

While steeping bonito flakes, reconstitute 1 Tbsp cut wakame in a bowl of cold water. Distribute wakame and cut tofu into soup bowls.

Remove 1 cup of dashi broth and mix with miso paste. Stir until smooth and then return to pot. Stir contents to distribute.

Pour broth over prepared soup bowls. Garnish with scallions and serve.