Heat oil in large nonstick skillet. Add onion; sauté 2 minutes. Add pepper; sauté 3 minutes.
Increase heat to medium-high. Stir in chicken pieces; saute 5 minutes or until no longer pink in center. Stir in tomato, duck sauce, ketchup, vinegar, soy sauce and cornstarch mixture. Bring to boiling; cook, stirring, until thickened, about 1 minute. To serve, spoon over rice. Makes 4 servings.