Rub rock salt and liquid smoke into pork surface. Wrap meat in leaves; enclose in heavy aluminum foil. Bake, covered, at 500 degrees for 1/2 hour; reduce to 325 degrees and bake for 3 1/2 hours. Shred meat into bite-sized pieces and serve with roasting liquid. For a different flavor, substitute banana, taro or spinach leaves for ti leaves.