1 c. ketchup
1/4 c. packed brown sugar
2 tbsp. red wine vinegar or cider vinegar
2 tsp. soy sauce
1 tbsp. dried minced onion
1/4 tsp. celery seed
1/2 tsp. salt, divided
1/4 tsp. crushed red pepper flakes, optional
dash liquid smoke, optional
4 boneless skinless chicken breast halves
1 tbsp. vegetable oil

In a saucepan, combine the ketchup, brown sugar, vinegar, soy sauce, onion, celery seed, 1/4 teaspoon salt, pepper flakes and liquid smoke if desired. Cook and stir over low heat for 10 minutes.

Meanwhile, rub chicken with oil and sprinkle with remaining salt. Grill, covered, over medium heat for 3 minutes on each side. Set aside 1/2 cup barbecue sauce for serving. Brush half of the remaining sauce over chicken. Grill 4-6 minutes longer or until chicken juices run clear, turning and basting occasionally with sauce. Serve with reserved sauce.