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 - 58 calories, 3 g fat (32% calories from fat), 8 g protein, 7 g carbohydrate, 5 g fiber, 0 mg cholesterol, 446 mg sodium