With a knife, pierce the skin a few times, making sure not to cut through the meat.
Pour vinegar over and massage on meat. Rub salt, garlic powder, and pepper all over the meat.
Refrigerate, uncovered and skin side up, overnight to chill.
With paper towels, pat down surfaces of meat to completely dry. Arrange on a roasting pan fitted with a rack.
Bake, uncovered, in a preheated 180 F oven for about 4 ½ to 5 hours.
Increase temperature to 320 F and continue to cook for about 1 ½ to 2 hours or until meat is cooked through and browns.
Increase temperature to 430 F and continue to cook for about 30 to 40 minutes or until skin is very crisp and a thermometer inserted in the center of the pork reads 145 F.
Remove from oven and allow to rest for about 10 to 15 minutes before slicing.