Wok-seared beef strips are coated in a robust black pepper sauce with onions and bell peppers. Packed with protein and deeply savory, this quick stir-fry is a satisfying family dinner option.
Mix the beef strips with 1/2 tablespoon soy sauce and the cornstarch in a bowl; let marinate for 10 minutes while you prep vegetables.
Heat a wok or heavy skillet over high heat. Add 1 tablespoon vegetable oil and swirl to coat. When just smoking, add the beef in a single layer. Sear for 1-2 minutes, stirring to brown, then transfer to a plate (beef will finish cooking later).
Add the remaining 1 tablespoon oil to the wok. Toss in onions and both bell peppers. Stir-fry on high heat for 2-3 minutes until edges are lightly charred but vegetables remain crisp.
Return the beef to the wok, pour in soy sauce, oyster sauce, water, black pepper, and sugar. Toss well, scraping up any browned bits, and stir-fry for 1-2 minutes until sauce thickens and everything is evenly coated.
Taste and adjust seasoning as desired. Serve immediately over steamed rice or as desired for a complete meal.