Place the pork in a large pan. Make 8-10 small slits (about 1-2 inch deep) on the skin side and insert (whole) garlic cloves into the slits.
Turn the pork over (skin side down) and make about 10-12 small slits (about 1-2 inch deep) in the meat. Use a ladle or spoon to pour the marinade into the slits.
Then pour the remaining marinade over the pork. Sprinkle 1 teaspoon of salt over the pork, if desired.
Turn the meat again so that the skin side is up. Seal the bag by making a tight knot or cover the pan well using a generous amount of plastic wrap.
Marinate in the refrigerator overnight. Remove from the refrigerator 30-45 minutes before roasting (provided it’s cool in your kitchen).
Roast at 325°F for 6-7 hours until it reaches at least 170° F and the meat has pulled away from the bone on one end. Tent about 1½-2 hours into the roasting time.
To crisp the skin, turn it over skin side up. Brush with salted water several times. Switch the oven to the low broiler setting. Broil for 2-4 minutes or until skin starts to bubble.