1.Combine brown sugar, salt, paprika, garlic powder, onion powder, black pepper and cayenne in a small bowl and mix well. Take out pork butt and dry well with paper towels then place in a large bowl.
2.Rub the entire roast with the mustard to coat. Generously apply the dry rub, pressing it into the mustard, to completely cover the butt. Cover with plastic wrap and place into the refrigerator for 8 to 12 hours.
3.An hour before smoking, remove the roast from the fridge. Preheat smoker to 225 degrees and fill water pan halfway up with water. Add wood chips to the drawer.
4.Place the roast on the upper rack of the smoker insert meat thermometer into the roast at one end. Smoke for approximately 8 hours.
5.Replenish wood chips every 60 minutes. At 2 hour intervals spray some apple cider vinegar on the roast just to moisten it. It is okay to turn the roast over once, but not necessary.
6.At 8 hours, check the internal temperature of the meat. It should read 190 degrees or even a little higher. If it isn’t quite up to temperature continue smoking.
7.Allow the fully cooked roast to rest for at least 20 to 30 minutes until cool enough to handle and to be able to remove the bone. Place the pork juices into a fat separator and discard the fat. After the pork has cooled enough to touch, place it on a clean cutting board and pull the roast using 2 forks to shred the meat into strands.
8.Place the pulled pork adding some juices to moisten in a large serving bowl. Serve immediately.