Prepare the Chicken: In a bowl, season the chicken with salt and half of the black pepper. Set aside for 10 minutes.
Cook the Chicken: Heat oil and butter in a pan over medium-high heat. Add the chicken pieces and stir-fry until golden brown. Remove and set aside.
Sauté the Garlic: In the same pan, add minced garlic and sliced onions. Cook until fragrant.
Prepare the Sauce: Add soy sauce, oyster sauce, chicken broth, honey, vinegar, and remaining black pepper. Stir well.
Combine Ingredients: Return the chicken to the pan and toss it in the sauce.
Thicken the Sauce: Add the cornstarch slurry and mix until the sauce thickens.
Add Vegetables: Stir in the sliced bell peppers and cook for 2 more minutes.
Final Touch: Drizzle sesame oil, mix well, and turn off the heat.
Garnish & Serve: Sprinkle chopped spring onions on top and serve hot with rice or noodles.