Impromptu miso soup

2 1/4 cups water
2 ounces firm or extra-firm Tofu, drained and cut into 1/4-inch dice (about 1/4 cup)
1 tablespoon sweet white Miso
2 teaspoons Barley miso
1 tablespoon instant wakame flakes (see note) or 1/2 cup chopped fresh Spinach or Bok choy leaves
1 scallion, very thinly sliced, for garnish

1. Bring the water to a boil in a medium-sized saucepan.
2. Ladle out about 1/2 cup of the boiling water and pour it into a glass measuring cup. Add the Tofu to the pan. Reduce the heat to medium, cover and cook for 1 to 2 minutes.
3. While the tofu is cooking, blend the two misos into the hot water by mashing the paste against the sides of the cup with a fork and stirring vigorously.
4. Just before serving, add the wakame or fresh greens to the saucepan and simmer the soup uncovered until the wakame is reconstituted, about 30 seconds, or the fresh greens are tender, 1 to 2 minutes.
5. Turn off the heat and stir in the Miso broth. Ladle into bowls, garnish with the scallion, and serve immediately.