Place the water and shiitake in a medium saucepan, cover and bring to a boil. Reduce the heat to medium-low and simmer about 10 minutes. Add onions and carrots and simmer 3 minutes. Reduce heat to low and add the wakame, Chinese cabbage, tofu and puréed miso. Simmer without boiling for 2 to 3 minutes. Ladle into serving bowls and garnish with scallions.
Per serving - 100 calories, 4 gram fat (25% calories from fat), 13 gram protein, 15 gram carbohydrate, 8 gram fiber, 0 milligram cholesterol, 448 milligram sodium