Sauteed Chicken with Onion

1 1/2 lbs. medium onions
4 boneless, skinless chicken breast halves (4-5 oz. each)
1/2 tsp. salt
1/2 tsp. pepper
4 tsp. olive oil
2 Tbs. sugar
1/3 cup reduced-sodium chicken broth
1 tsp. chopped fresh rosemary
1 tsp. chopped fresh thyme
1 Tbs. red wine vinegar

Cut onions into 6 wedges each. Sprinkle chicken with 1/4 tsp. salt and 1/4 tsp. pepper.
Coat large nonstick skillet with cooking spray. Add 2 tsp. olive oil and heat over medium-high heat for about 30 seconds. Add chicken and saute until browned, about 3 minutes on each side; transfer to plate.
Reduce heat to medium and add remaining oil. Saute onions, 1 tbs. sugar, and remaining salt and pepper until onions turn golden-brown and carmelize, about 8 minutes. Stir frequently, breaking onions apart as they cook. Add broth and boil until it evaporates, about 2 minutes.
Stir in rosemary, thyme, and remaining sugar. Return chicken to skillet and sprinkle with vinegar. Cook uncovered until juices of chicken run clear, about 4 minutes.
Divide into 4 portions. One serving equals one chicken breast topped with about 1/2 cup onions.