In a small bowl, combine soy sauce, cornstarch, and crushed red pepper; set aside.
In a wok or large skillet, heat the oil over high heat until hot. Add the garlic, broccoli, peppers, onion, and mushrooms. Stir-fry for 5 minutes, or until the vegetables are almost crisp-tender.
Add shrimp and stir for 2 minutes.
Add the snow peas and stir-fry for 3 to 4 minutes, or until the snow peas turn bright green and shrimp is cooked through.
Add the soy sauce mixture, and stir-fry for 1 to 2 minutes, or until the sauce thickens. Serve immediately.