Pat ribs dry and remove membrane from back.
Rub the ribs with mustard and then the dry rub.
Allow the seasonings to sit at least 20 minutes, then place on smoker meat side up.
Smoke uncovered for 3 hours. Halfway through, check on the ribs and if they appear dry, baste the ribs with butter and apple cider vinegar.
After 3 hours on the smoker, transfer the ribs to buttered foil, bone side up and meat side down.
Seal the foil and place the ribs back on the smoker for 2 hours.
Remove ribs from foil and transfer back to the smoker meat side up. Smoke the ribs an additional hour.