For sauce, bring all of the ingredients together in a medium saucepan, and simmer for about 20 minutes, stirring often. Let the sauce cool to room temperature. It can then be used right away. Reserve about 1 cup to be used with the chicken and store the remaining sauce in an airtight container in the refrigerator.
In a large resealable plastic bag, add the chicken and about 2/3 cup of the sauce. Coat the chicken well, and refrigerate for at least 1 hour, or up to 24 hours.
Remove the chicken from the refrigerator, and light your grill to a medium - high setting. Add the chicken to the hot grill, skin side down. Cover with lid and cook for about 5-7 minutes, and then flip. Brush with the additional 1/3 cup of sauce, and cook for another 5-7 minutes. Chicken is done when white all the way through, and juices run clear. Serve right away.