Heat the olive oil for the sauce in a medium saucepan and sauté the onions for 1 to 2 minutes. Drain and coarsely chop the maitake. The soaking water can be discarded or used for soup stock. Add the maitake, carrots and red pepper and sauté for another 5 minutes. Add the spaghetti sauce, diced tomatoes and basil. Cover and bring to a boil. Reduce the flame to low and simmer for about 15 minutes. Add the shoyu and simmer another 5 minutes.
While the sauce is cooking, cook the pasta as package directs. When done, remove, drain and toss the pasta with a little olive oil to prevent sticking. Place on individual serving plates. Ladle the sauce over each serving.
Per serving - 362 calories, 8 g fat (19% calories from fat), 15 g protein, 58 g carbohydrate, 12 g fiber, 0 mg cholesterol, 360 mg sodium