First Step: PREPARE THE BEEF

1. Slice the Beef: Start by slicing the flank steak thinly against the grain. This is crucial for ensuring that the beef stays tender and doesn’t become chewy. Cutting against the grain helps break up the muscle fibers, making each bite more tender.
2. Marinate the Beef: Place the sliced beef in a bowl and add 1 tablespoon of soy sauce, 1 teaspoon of cornstarch, and a pinch of black pepper. Toss everything together until the beef is evenly coated. Let it marinate for 10-15 minutes while you prepare the vegetables and sauce. This will help the beef absorb flavor and stay juicy while cooking.

Second Step: PREPARE THE STIR-FRY SAUCE

1. Combine the Ingredients: In a small bowl, whisk together the remaining soy sauce, oyster sauce, rice vinegar, brown sugar, beef broth, and cornstarch. This will form your stir-fry sauce. The cornstarch in the sauce will help thicken it as it cooks, creating a glossy, smooth coating for the beef and vegetables.
2. Set Aside: Once the sauce is mixed, set it aside. The cornstarch may start to settle, so give it a quick stir before adding it to the pan later.

Third Step: COOK THE BEEF

1. Heat the Oil: In a large skillet or wok, heat 1 tablespoon of vegetable oil over medium-high heat. You want the pan to be very hot to sear the beef quickly and lock in the juices.
2. Stir-Fry the Beef: Add the marinated beef to the pan in a single layer, being careful not to overcrowd the pan. Let it sear for 2-3 minutes without stirring to get a nice brown color. Once the beef is browned on one side, stir-fry it for an additional 2-3 minutes until fully cooked but still tender. Remove the beef from the pan and set it aside.

Fourth Step: COOK THE VEGETABLES

1. Stir-Fry the Vegetables: In the same pan, add the remaining 1 tablespoon of vegetable oil. Add the sliced onion, bell peppers, garlic, and ginger. Stir-fry the vegetables for about 3-4 minutes until they are tender-crisp. You want them to retain some crunch, so be sure not to overcook them.
2. Add the Beef Back In: Once the vegetables are cooked, return the beef to the pan. Stir everything together so the beef and vegetables are evenly mixed.

Fifth Step: ADD THE SAUCE AND THICKEN

1. Add the Sauce: Pour the prepared stir-fry sauce over the beef and vegetables. Stir to coat everything evenly.
2. Thicken the Sauce: Allow the sauce to simmer for 2-3 minutes, or until it thickens to your desired consistency. The cornstarch will help the sauce cling to the beef and vegetables, creating a glossy, flavorful coating.

Sixth Step: GARNISH AND SERVE

1. Garnish: Once the sauce has thickened, remove the pan from the heat. Garnish the dish with chopped green onions and a sprinkle of sesame seeds for added flavor and texture.
2. Serve: Serve the Chinese Pepper Steak hot, paired with steamed rice, noodles, or even wrapped in lettuce leaves for a low-carb option.