In a large saucepan, combine the stock, sweet potatoes, onions, celery, mushrooms, turnips, parsnips, carrots, soy sauce, mirin, sake, garlic and ginger. Bring to a boil.Reduce the heat and simmer for 25 minutes.
Add the zucchini and yellow squash. Simmer for an additional 5 minutes. Add the tofu and simmer 5 minutes more. Season to taste with the pepper, Szechuan peppercorns, and salt. Garnish with chopped green onions and serve. Serving size� 1/2 cups 232 calories 3.6 g fat 0 mg chol 1,589 mg sod Eat More, Weigh Less, by Dean Ornish, M.D./MM by DEEANNE