Step 1: Marinate the Chicken

1. In a mixing bowl, combine the chicken pieces, cornstarch, soy sauce, and oyster sauce. Toss until the chicken is evenly coated and set aside for 10 minutes while you prepare the other ingredients.

Step 2: Prepare the Sauce

1. In a small bowl, whisk together soy sauce, oyster sauce, dark soy sauce (if using), rice vinegar, honey, black pepper, and chicken broth or water. Set the sauce aside.

Step 3: Cook the Chicken

1. Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat.
2. Add the marinated chicken to the pan in a single layer. Cook for 3-4 minutes on each side until golden brown and cooked through. Remove the chicken from the pan and set it aside.

Step 4: Sauté the Vegetables

1. In the same skillet, add 2 tablespoons of vegetable oil.
2. Sauté the sliced onion, green bell pepper, and red bell pepper for 3-4 minutes until they are slightly softened but still crisp.
3. Add the minced garlic and ginger, stirring for 30 seconds until fragrant.

Step 5: Combine and Cook

1. Return the cooked chicken to the skillet and pour in the prepared sauce. Toss everything together to ensure the chicken and vegetables are evenly coated.
2. Cook for 2-3 minutes, stirring frequently, until the sauce thickens and becomes glossy. Drizzle sesame oil over the dish for extra flavor if desired.

Step 6: Garnish and Serve

1. Garnish the Black Pepper Chicken with chopped scallions.
2. Serve hot over steamed rice or noodles, and enjoy!