In a wok or large skillet, heat the oil.
Stir-fry the beef, garlic and ginger over high heat just until the steak is partially browned and some pink remains, maybe 30 seconds to a minute.
Add the onions and peppers; stir-fry until tender-crisp about 1 minute or so.
Stir in the soy sauce and oyster sauce.
Cook very briefly just until the sauce coats everything.
Serve over rice or quinoa, for a low carb version version serve over cauliflower rice or a bed of spinach