Whisk together the first 10 ingredients. Add onion; set aside 1/4 cup. Pour remaining marinade into a large resealable plastic bag; add chicken. Seal bag and turn to coat; refrigerate at least 8 hours or overnight, turning occasionally. , Drain and discard marinade. Grill the chicken, covered, over indirect medium heat for 45 minutes or until juices run clear, turning and basting with reserved marinade every 8-10 minutes., To bake chicken: After marinating, place chicken in a greased 15x10x1-in. baking pan. Pour the remaining marinade over the chicken. Bake, uncovered, at 350° for 1-1/4 hours or until juices run clear, basting occasionally.