Step 1

In a bowl, mix soy sauce, oyster sauce, black pepper, graduated sugar, minced garlic, minced ginger, and cooking wine.

Step 2

Combine the thinly sliced flank steak with soy sauce and cornstarch in a large mixing bowl. Ensure each piece is well-coated. Let it marinate for about 15 minutes.

Step 3

Lightly spray the air fryer basket with cooking oil or line the bottom with parchment paper. Spread marinated beef slices in a single layer in the basket, ensuring they don’t overlap. Set the air fry temperature to 400 degrees F (205°C) and the cooking time to 6-7 minutes, shaking or flipping halfway through.

Step 4

In a wok or large skillet over medium heat, quickly sauté the bell peppers and onions until they are slightly tender but still have some crunch. Add the air-fried beef slices to the wok. Pour the sauce mixture over the beef and veggies. Stir well to coat everything evenly. Cook for an additional 2-3 minutes.

Step 5

Transfer the black pepper beef to a serving plate. Garnish with sliced green onions if desired. It is best enjoyed hot with steamed rice.