Place the water and maitake in a medium saucepan and let soak for 10 to 15 minutes. Remove maitake and slice, if desired. Place maitake back in the pot, add the dried tofu, cover and bring to a boil. Reduce heat to medium-low and simmer about 10 minutes. Reduce heat to low and add the wakame, bok choy and puréed miso. Simmer without boiling for 2 to 3 minutes. Ladle into serving bowls and garnish with scallions.
Per serving - 87 calories, 3 g fat (26% calories from fat), 16 g protein, 4 g carbohydrate, 3 g fiber, 0 mg cholesterol, 452 mg sodium