Preheat your pellet grill to 250°F (107°C). Fill the hopper with your preferred pellets.
Removing the membrane from the bone side of the racks.
Coat both sides of the ribs with a thin layer of yellow mustard.
Generously season both sides of the ribs with the dry rub, ensuring an even coating. Let sit for 15-30 minutes.
Mix the apple juice and vinegar together in a clean spray bottle.
Place the ribs on the pellet grill, bone side down. Close the lid and smoke for 3 hours. In the last hour, spray the ribs 2-3 times (about 8 sprays each) with the apple mixture.
After 3 hours, carefully remove the ribs from the grill. Cut two large pieces of aluminum foil (large enough to fold over the ribs to form a packet).
Mix any remaining spray with the BBQ sauce in a bowl. Pour half the sauce onto each piece of foil. Place a rib rack, meat side down in the liquid to coat the top, then turn it over so it’s bone side down again.
Tightly wrap the ribs in the foil.
Return the foiled ribs to the grill and continue cooking for an additional 2 hours.
Carefully remove the foil packets from the smoker and let rest for 30 minutes before opening.