1. In a wok or wide pan on high heat, heat 1 tbsp of oil. Add shiitake mushrooms and cook for until fragrant.
2. Add snow peas and baby oyster mushrooms and cook for another 10 secs. Remove from pan and keep warm.
3. 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.
4. Wipe down wok as needed. Add the remaining 1 tbsp oil. Add onions and garlic, stir until softened.
5. 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.