In a mixing bowl, combine the sliced beef with soy sauce, cornstarch, rice wine, and black pepper. Mix well and let it marinate for at least 15 minutes.

In a small bowl, mix together soy sauce, chili paste, sugar, vinegar, and sesame oil. Set aside.

Heat vegetable oil in a wok over high heat. Once hot, add the marinated beef in batches, frying until crispy. Remove and drain on paper towels.

In the same wok, add a little more oil if needed, then stir-fry garlic, ginger, bell peppers, and onion until just tender.

Add the crispy beef back to the wok along with the sauce. Stir well to coat everything evenly. Serve hot.