In a large pot, saute the garlic, scallions & green bell pepper in oil over medium heat until the peppers are tender-crisp, about 2 minutes. Add the mushrooms, reduce the heat to low & saute for 3 minutes. Add the tomatoes & snow peas. Cover & simmer for 10 minutes. Cook the pasta until al dente. Drain. Stir the cayenne & tamari into the tomato sauce & spoon over the hot pasta. Serve immediately.