Make the beef marinade by combining the sliced rib eye, baking soda, cornstarch, and 2 tablespoons soy sauce in a bowl; toss to coat and set aside to rest.
Whisk the stir-fry sauce in a separate bowl: combine the 2 tablespoons low-sodium soy sauce, oyster sauce, dark soy sauce, sugar, rice vinegar, and sesame oil; set aside.
Heat 2 tablespoons olive oil in a large skillet or wok over high heat until hot.
Add the marinated beef in a single layer and let it sear undisturbed for about 2 minutes, then toss briefly to brown the other side.
Add the minced garlic, sliced onion, and julienned ginger to the pan and cook, stirring, for 1 minute.
Stir in the quartered mushrooms and cook for about 2 minutes until they begin to brown.
Pour the prepared sauce over the beef and vegetables and toss everything together until the sauce is well distributed and heated through, about 30–60 seconds.
Remove from heat, garnish with sliced green onions, and serve immediately.
