Marinate the chicken slices in soy sauce and cornstarch for 30 minutes.
Prepare your vegetables by slicing the bell pepper, onion, and mincing the garlic and ginger.
Heat a skillet or wok over medium-high heat and add vegetable oil.
Add the marinated chicken to the pan in a single layer and cook until golden brown, approximately 5-7 minutes.
Add the sliced onion, bell pepper, garlic, and ginger to the pan.
Stir in the black pepper, ensuring it’s evenly distributed, and adjust seasoning if necessary.
Cook for an additional 3-4 minutes until the vegetables are tender-crisp.
Serve hot over rice or noodles, garnished with additional black pepper if desired.