Marinate the Beef: In a mixing bowl, whisk together soy sauce, oyster sauce, and cornstarch until smooth. Add your sliced beef to the mixture, ensuring each piece is fully coated. Let it marinate for at least 15 minutes; for a more intense flavor, consider marinating for 30 minutes.

Prep Vegetables: While the beef marinates, prepare your vegetables. Slice the bell peppers into strips and the onion into thin wedges. Mince the garlic and grate the ginger.

Sear Beef: Heat a large skillet or wok over high heat. Once the oil shimmers, add the marinated beef in a single layer, allowing it to sear undisturbed for 1-2 minutes on each side until browned.

Cook Vegetables: In the same skillet, add a little more oil if needed, and toss in the sliced bell peppers and onion. Sauté for 3-4 minutes until they are tender yet still crisp.

Combine Ingredients: Add the minced garlic and grated ginger to the sautéed vegetables, stirring for about 1 minute until aromatic. Return the browned beef to the skillet and pour in your beef broth or water.

Season and Serve: Finally, season your Pepper Steak with salt and pepper to taste. Serve hot over a bed of rice or noodles.