Prep Beef: Add the beef, baking soda, cornstarch and 2 tbsp of soy sauce to a bowl. Toss everything together and set aside.
Combine Stir Fry Ingredients: Combine all the stir fry sauce ingredients together in a bowl and set aside.
Cook: Heat the olive oil in a large skillet or wok over high heat. Add the beef and spread it out. Don't touch it for 2 minutes, allowing it to sear. Toss it around a bit, then add the garlic, onion, ginger and cook for 1 minute. Stir in the mushrooms and cook for an additional 2 minutes, just until they start to brown a bit. Pour the sauce over everything and toss until well combined.
Garnish & Serve: Garnish with green onions and serve.
