1-First Step: Gather and prepare your ingredients by cutting 1 pound of flank steak against the grain into thin 1/4-inch slices, then marinate the beef slices with 3 large beaten egg whites, 1/4 teaspoon salt, and 1 teaspoon cornstarch for 30 minutes to 1 hour.

2-Second Step: Prepare the sauce by whisking together 1/2 cup water, 1/4 cup sugar, 3 tablespoons ketchup, 6 tablespoons hoisin sauce, 1 tablespoon low sodium soy sauce, 2 teaspoons oyster sauce, 4 teaspoons sweet chili sauce, 1 teaspoon crushed red peppers, and 2 tablespoons apple cider vinegar in a bowl.

3-Third Step: Coat the marinated beef by first discarding the excess marinade, then tossing the slices in 2 tablespoons of cornstarch. Next, toss them in the remaining 2 tablespoons of cornstarch, shaking off any excess before frying.

4-Fourth Step: Heat 1 cup vegetable oil in a small saucepan over medium-high heat. Fry the beef slices in batches for 2-3 minutes until golden brown, then remove and drain on paper towels.

5-Fifth Step: In a large pan, heat 2 tablespoons of the used frying oil over high heat. Add 1 sliced yellow onion and 1 red bell pepper cut into 1-inch pieces, cooking for 2-3 minutes until the edges start to caramelize, then add 4 minced garlic cloves and cook for a few seconds until fragrant. Remove the vegetables from the pan.

6-Sixth Step: Add the prepared sauce to the large pan and cook over high heat, stirring, for 3-5 minutes until it thickens.

7-Final Step: Return the fried beef and cooked vegetables to the pan with the thickened sauce, tossing everything together to coat evenly, then serve immediately for the best flavor and texture.