1. Cut beef in small strips. 2. In a bowl mix cornstarch and soy sauce. 3. Mix beef in this mix. 4. Let marinate for 2 hours. 5. Remove the meat from the marinade. 6. Heat wok with 1/2 of the peanut oil. 7. Add the ginger and garlic and stir fry until they start to turn brown. 8. Add the meat and stir fry and fry until done. 9. Remove the meat from the wok and set aside. 10. Heat the wok with the remaining oil. 11. Add the mushrooms and onion and sautee. 12. Add the oyster sauce and sugar and a pinch of pepper. Stir fry for 2-3 minutes. 13. Add the meat to the sauce mixture. Stir fry for an additional 1-2 minutes. 14. Serve.
