Start by adding 4 cups of water and the kombu to a pot. Heat it over medium until it simmers but does not boil.

Remove the kombu, then add the bonito flakes and let it simmer for about 5 minutes. Skim off any foam that surfaces.

Use a fine mesh sieve or cheesecloth to strain the broth. Discard the bonito flakes, then return the clear broth to the pot. Bring it back to a gentle simmer.

Add the soaked seaweed and cubed tofu to the broth. Let it simmer for about 3 minutes until the tofu is heated through and the seaweed softens.

Turn off the heat. In a separate bowl, mix a few spoonfuls of hot broth with the miso paste until smooth, then stir the mixture back into the pot.

Avoid boiling the miso to keep its flavor intact.

Ladle the soup into bowls and then sprinkle with chopped scallions. Serve your homemade miso soup immediately for the best experience.