1Place 1 chicken breast half, boned side up, between two pieces of plastic wrap or waxed paper.
2Working from center, gently pound chicken with rolling pin or flat side of meat mallet until about 1/4" thick; repeat with remaining chicken pieces.
3In 12x8" baking dish or plastic bag, combine all marinade ingredients; mix well to dissolve sugar.
4Add chicken; turn to coat.
5Cover dish or seal bag; refrigerate 1 to 2 hours, turning several times.
7Drain chicken, reserving marinade.
8When ready to barbecue, place chicken on gas grill over low heat or on charcoal grill 4 to 6 minches from medium coals.
9Cook 10 to 15 minutes or until chicken is no longer pink, turning once and brushing with reserved marinade.
10Discard any remaining marinade.