Using poultry shears, split chicken open by cutting down backbone. Flatten a bit by pounding with your hand so that chicken is "butterflied." Mix remaining ingredients in a large bowl; add chicken and coat well. Cover and marinate in refrigerator for 2 hours.
Preheat a grill to medium-hot. Place chicken, skin side down, on grill and cook for 25 minutes, basting occasionally with marinade. Turn chicken over and continue cooking until chicken is tender and juices run clear, about 20 minutes longer. Discontinue basting during last 10 minutes of cooking and discard marinade.
Makes 4 servings.