1. Heat oven to 300 degrees . Let pork sit at room temperature 30 minutes before cooking; season with salt and pepper. Wrap tightly in aluminum foil, then place on a rimmed baking sheet fitted with a rack. Slow roast at 300 degrees for 7 hours, until pork reaches 200 degrees in the thickest part and pulls apart easily with a fork.Mustard Barbecue Sauce
2. During the last 20 minutes of roasting, heat butter in a small pot over medium-low heat. Add onion and garlic. Cook 3 minutes. Whisk in mustard, dry mustard, vinegar, brown sugar and Tabasco. Reduce heat to medium-low and simmer 15 minutes.
3. Allow pork to cool slightly, then shred with 2 forks. Discard fat, skin and bone. Toss with barbecue sauce. Serve pork alongside buns, if desired.