Place all ingredients, except the shoyu and scallions, in a soup pot, cover and bring to a boil. Reduce the flame to medium-low, and simmer for 15 to 20 minutes. Reduce the flame to low, and add the shoyu. Simmer 3 to 4 more minutes. Serve, and garnish with scallions.
Per serving - 96 calories, 0 g fat (4% calories from fat), 6 g protein, 17 g carbohydrate, 4 g fiber, 0 mg cholesterol, 230 mg sodium