Ingredients:
1 lb (450 g) beef sirloin or flank steak, thinly sliced against the grain
2 tbsp vegetable oil
1 large green bell pepper, sliced
1 large red bell pepper, sliced
1 large onion, sliced
3 cloves garlic, minced
1 tsp fresh ginger, minced
1/4 cup soy sauce
2 tbsp oyster sauce
1 tbsp hoisin sauce (optional)
1 tsp cornstarch mixed with 2 tbsp water (slurry)
1/4 tsp black pepper (adjust to taste)
Cooked rice or noodles, for serving
Instructions:
Prepare the beef: Pat beef slices dry and season lightly with black pepper.
Cook the beef: Heat 1 tbsp vegetable oil in a large skillet or wok over high heat. Stir-fry beef in batches for 2–3 minutes until browned but not fully cooked. Remove and set aside.
Cook vegetables: Add remaining oil to the skillet. Stir-fry onions and bell peppers for 3–4 minutes until slightly tender but crisp. Add garlic and ginger and sauté for 30 seconds until fragrant.
Combine beef and sauce: Return beef to the skillet. Add soy sauce, oyster sauce, and hoisin sauce (if using). Stir well to coat.
Thicken the sauce: Pour in cornstarch slurry and stir until the sauce thickens slightly, about 1–2 minutes. Adjust seasoning with more black pepper if desired.
Serve: Serve hot over steamed rice or noodles.