Combine first 7 ingredients, stirring with a whisk.
Place chicken in a large shallow dish; pour half of hoisin mixture over chicken, turning to coat, reserve remaining hoisin mixture. Cover and chill chicken mixture 3 hours, turning occasionally.
Prepare grill or broiler. Remove chicken from dish; discard marinade. Place chicken on grill rack or broiler pan coated with cooking spray, cook 4 minutes on each side or until done, basting occasionally with reserved hoisin mixture.