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 gram fat (32% calories from fat), 8 gram protein, 7 gram carbohydrate, 5 gram fiber, 0 milligram cholesterol, 446 milligram sodium