Heat your smoker to 250℉.
Trim excess fat off pork butt. Slather the entire pork butt with hot Chinese mustard, and then generously season with Headwaters BBQ Ringing Rock Rib Rub on all sides and let sit for 20 minutes.
Place the pork butt fat side up in the smoker and smoke until the internal temperature reaches 160℉, about 4 to 5 hours. Remove the pork butt.
Layer several large pieces of aluminum foil on top of each other, ensuring they are wide enough to wrap the pork butt entirely on all sides. Place the pork butt in the center, then bring up the sides of the foil. Pour the apple cider on top of the pork butt. Wrap the foil tightly around the pork.
Place the pork butt back into the smoker and cook until the internal temperature reaches 204℉, another 4 hours.
Remove from the smoker, and let the pork rest for 45 minutes in the foil packet.
Remove the pork from the foil, and start shredding the meat, discarding the bone and any excess fat. Blend in the Montana Rooster Vinegar Sauce with the meat.