01 - Combine the sliced beef with soy sauce, Shaoxing wine, cornstarch, and black pepper in a bowl. Mix thoroughly to coat each piece. Allow to marinate for 10-15 minutes at room temperature.
02 - Whisk together soy sauce, oyster sauce, hoisin sauce, sugar, beef broth, and cornstarch in a small bowl until cornstarch is fully dissolved. Set aside for later use.
03 - Heat 1 tablespoon vegetable oil in a large wok or skillet over high heat until smoking. Arrange marinated beef in a single layer without overcrowding. Sear for 1-2 minutes until browned but slightly undercooked. Remove beef from pan and set aside.
04 - Add remaining tablespoon of oil to the wok. Toss in onions, bell peppers, garlic, and ginger. Stir-fry vigorously for 2-3 minutes until vegetables are crisp-tender and fragrant.
05 - Return seared beef to the wok. Pour in prepared sauce and toss all ingredients together. Continue stir-frying for 1-2 minutes until sauce thickens and coats everything evenly. Season with additional black pepper to taste.
06 - Transfer to a serving platter immediately. Serve hot alongside steamed white rice for a complete meal.