Beef in oyster sauce

Beef aromatic stir fry recipe😋😋😋
Ingredients:
1 lb. beef tenderloin thinly sliced
3 tablespoons oyster sauce
1 teaspoon soy sauce
1 ½ tablespoons cornstarch
1/2 teaspoon ground black pepper
1- piece green bell pepper sliced into thick strips
1- piece red bell pepper sliced into thick strips
1/2 cup cooking oil
Instructions