Directions

1. Trim fat from pork, leaving fat cap about 1/4-inch thick. Pat pork dry with paper towels. Place on a large piece of plastic wrap. Spread mustard on all sides of pork. In a small bowl stir together brown sugar, salt, paprika, chili powder, black pepper and garlic powder. Coat all sides of pork with spice mixture. Wrap the pork tightly in the plastic wrap. Place on a tray and chill for at least 1 hour or overnight.
2. Preheat oven to 325 degrees F. Line a shallow roasting pan with foil. Place a rack in the pan. Unwrap pork and place on the rack. Roast, uncovered, for 4 hours. Wrap roast with a double thickness of foil and return to the rack. Roast for 2 hours more or until an instant-read thermometer inserted in meat registers at least 190 degrees F. Remove from oven. Let roast stand for 30 minutes to 1 hour (this allows the "bark" or "crust" to soften). Unwrap. Using 2 forks, pull the pork apart, removing any large pockets of fat as you pull. Serve with pickles,onion slices, and Spicy Vinegar.
3. Slow Cooker directions: Prepare recipe through step 1 except reduce the salt to 1 tablespoon. Unwrap roast and place in a 6-quart slow cooker. Cover; cook on low-heat setting for 10 to 12 hours or on high-heat setting for 5 to 6 hours (190 degrees F). Remove meat from cooker, strain cooking juices. When cool enough to handle, use 2 forks to pull the pork apart, removing any large pockets of fat as you pull. Drizzle with cooking juices, if you like, to reach desired moistness. Serve as directed.
4. Spicy Vinegar: Stir together all ingredients in a non-reactive container. Cover and store at room temperature at least 3 days or up to 6 months (the flavor will mellow over time).