Preheat oven to 425°F. Grease a 2-quart baking dish.
Place chicken in the prepared dish. Sprinkle with cornstarch and toss to coat.
Stir in onion and bell peppers.
In a separate bowl, whisk together ketchup, vinegar, brown sugar, soy sauce, garlic, and ginger. Pour sauce over chicken and vegetables; stir to combine.
Bake, uncovered, for 25 minutes. Stir, return to the oven for 5-10 more minutes, or until chicken is cooked through and the sauce has slightly thickened. If you find that your sauce is too thick when the chicken is done baking, you can add a splash of warm water (as necessary), and stir to thin.
Serve over hot cooked rice, if desired. Garnish with sliced green onions, sesame seeds, and chopped peanuts.
Source:
theseasonedmom.com