Combine cornstarch and water. Set aside for last step. Wash and cut vegetables into uniform-size slices, strips or diagonal slices. Pat dry before frying. Combine cooking oil, garlic, and ginger root into frying pan to around 350 degrees. Cook slightly. Add prepared vegetables to heated oil (add more delicate vegetables like green onion, bean sprouts, and snow peas last). Stir vegetables in a folding motion until tender-crisp. Combine stock and soy sauce into pan and reduce heat. Pour corn starch mixture over vegetables. Cook just until sauce thickens.