Wash the chicken breasts and slice them into thin strips. Put them in a bowl.

Add soy sauce, black pepper, a little salt, and chili sauce to the chicken. Mix well and leave it for 5 minutes.

Slice the red bell pepper, green bell pepper, and onion. Mince the garlic cloves.

Add the chicken to the hot pan. Cook for 5–6 minutes until the chicken turns golden and is fully cooked. Stir often.

Add the minced garlic and cook for 30 seconds until fragrant.

Add the sliced onion, red bell pepper, and green bell pepper. Stir fry for 3–4 minutes until slightly soft but still crunchy.

Add oyster sauce, chili flakes, and a little more chili sauce if you like extra spice. Mix everything well.

Cook for another 1–2 minutes while stirring so the sauce coats the chicken and vegetables.

Turn off the heat and serve hot with rice or noodles.