Combine soy sauce, oyster sauce, sesame oil and garlic in a small bowl, set aside. Place a work or large skillet over high heat, add vegetable oil and ginger, cook for 30 seconds. Add mushrooms and garlic, stir-fry for 2 minutes. Add snap peas and cornstarch mixture, toss and cook for about 2 minutes until sauce thickens and peas are tender crisp.