Day before serving:
Score top and bottom of pork (about 3/4-inch deep) diagonally in a diamond pattern.
Coat pork well with sauce (use gloves). Cover well with plastic wrap; refrigerate overnight.
Day of:
Preheat oven to 275 degrees.
Remove plastic wrap; transfer pork to shallow roasting pan, or leave in the marinating dish (make sure there is sufficient space to hold the fat that cooks out). Cook uncovered, 7-8 hours. Meat can be pulled with tongs for serving. Service with mango jasmine rice and a nice salad or sautéed greens.
Use leftovers for pork sandwiches and taco meat.