Step 1

Combine the water and kombu in a large saucepan. Soak for 30 minutes.

Step 2

Turn the heat to medium-low. Once the water *almost* reaches a simmer, use tongs to remove and discard the kombu. Once the water reaches a simmer, turn the heat off and add the bonito flakes. Let the flakes soak for 2 minutes (or up to 10 if you prefer more intense umami flavor).

Step 3

Line a large fine-mesh strainer with a paper towel. Slowly pour the broth through the strainer into another heat-safe bowl, straining out and then discarding all of the dashi flakes. (Avoid pressing down the bonito flakes, which can make the broth slightly more bitter.) Return the broth to the saucepan.

Step 4

Add the tofu and half of the scallions to the broth and cook over medium-high heat until boiling. Add the wakame and turn off the heat.

Step 5

Add the miso to a small fine-mesh strainer (or you can use a ladle, see below). Carefully lower the strainer into the broth so that the miso is just submerged, then use chopsticks (or fork) to whisk the miso with the broth until it has completely dissolved.

Step 6

Heat the soup once more over medium-high heat until it *almost* reaches a simmer, then remove from heat. (It’s very important that the soup does not reach a boil.)

Step 7

Serve. Serve warm, garnished with the remaining scallions.