- In a small bowl, combine beef with the marinade ingredients. Stir to fully coat meat and let stand for about 10-15 mins.
- In another bowl, combine the sauce ingredients. Stir until well blended and set aside.
- With hands, gently squeeze meat to extract marinade. Add excess liquid into the bowl of sauce mixture (this is important as the cornstarch from the marinade will thicken the stir-fry sauce).
- In a wok or wide pan on high heat, heat 1 tbsp of oil. Add shiitake mushrooms and cook for until fragrant.
- Add snow peas and baby oyster mushrooms and cook for another 10 secs. Remove from pan and keep warm.
- Add 1 tbsp of oil to the pan. Add beef in a single layer and cook for about 3-4 mins per side. Do not overcrowd the pan, cook beef in batches if needed. Remove from pan and set aside.
- Wipe down wok as needed. Add the remaining 1 tbsp oil. Add onions and garlic, stir until softened.
- Add beef and vegetable mixture. Continue to cook, stirring occasionally, for about 2-3 mins or until heated through and coated with sauce. Serve hot with rice.