Marinate the beef with soy sauce, cornstarch, and a pinch of salt and pepper for 15 minutes.
Heat oil in a large skillet or wok over medium-high heat.
Add the beef and stir-fry until browned. Remove from the skillet and set aside.
Add onion, garlic, and ginger to the skillet and cook until fragrant.
Add cabbage and stir-fry until it begins to wilt.
Return the beef to the skillet.
Add oyster sauce, if desired, and adjust seasoning with salt and pepper.
Serve hot with rice
