In a large skillet add the oil and bring to a high heat. Next, add in the garlic and sauté until golden, about 1-2 minutes.
Next, add in the chicken pieces and sauté for 5 minutes, mixing occasionally.
Continuing on high heat, add in the peppers, onions, salt, and black pepper.
Sauté for 10-15 minutes, mixing occasionally, or cook until the peppers are tender.
Place the chicken with peppers and onions in a large serving dish or on top of brown rice.