Process vinegar, Knorr® Chicken flavor Bouillon, garlic, water, oil, and oregano in blender until smooth.
Slash chicken through the skin to the bone in several places. Rub Bouillon mixture into slashes and all over chicken. Place in large bowl; cover and marinate in refrigerator at least 4 hours or up to 24 hours.
Remove chicken from marinade. Place on oiled grill rack and pour any remaining marinade over top. Grill over indirect heat, turning occasionally, until thoroughly cooked, about 45 minutes.