Marinate beef slices with marinade ingredients for 30 minutes. Heat oil in wok and stir-fry marinated beef briskly, then dish up and set aside.
Heat wok with oil and stir-fry ginger and garlic until lightly browned and fragrant. Return the beef slices to the wok and stir-fry well. Add seasoning ingredients. Mix in thickening and spring onions. Dish out and serve hot.