Rub the ribs with mustard and then the dry rub.
Place the ribs on the smoker, meat side up.
Smoke uncovered for 3 hours, basting with butter and vinegar halfway through if necessary.
Drizzle butter on the bottom of a piece of foil and place the ribs there meat side down. Cook for 2 hours.
Remove from the foil and return to the smoker meat side up, then cook another hour.