Step 1Bring the Dashi to a boil in a medium saucepan, then reduce the heat to maintain a simmer.
Step 2In a small bowl, dissolve 3 1/2 tablespoons of the miso paste in a few tablespoons of the warm Dashi. Add the mixture to the saucepan. Taste and add more miso paste, Dashi or water, depending on how strong the soup tastes.
Step 3Add the tofu and mushrooms to the soup. Bring the soup to a quick boil once again, then remove it from the heat and pour the soup into individual bowls.
Step 4Sprinkle each bowl with chopped green onion. Serve immediately.
Variation: To make one of the most popular miso breakfast soups, Miso Soup With Wakame Seaweed and Tofu, follow this recipe but substitute 1/4 cup rehydrated wakame seaweed, chopped to 1-inch pieces, for the enoki mushrooms.