Rinse the ribs under cool running water. Pat them completely dry with paper towels. Set these aside.
In a small bowl, mix together the sugar, salt, pepper, garlic powder, paprika, and cayenne.
Coat the ribs with the mustard to cover all surfaces.
Pat the dry seasoning rub into the mustard to coat the ribs.
Set the ribs aside while you prepare your smoker.
Fill the hopper of the smoker with pellets.
Plug the smoker in and turn it on with the top open until a flame is established.
Set the temperature to 225˚F and preheat the smoker with the top closed until it comes to temperature, approximately 5 minutes.
Place the seasoned pork portions directly on the large rack of the grill.
If the grill has a probe thermometer insert it into the thickest portion of one of the ribs.
Close the lid and set a timer for 4 hours.
Spray the ribs with apple juice after 2 hours and again at 3 hours.
Check the internal temperature of the meat at 4 hours. You are looking for between 170˚F and 175˚F.
Mop or brush some BBQ sauce on the top of the ribs and smoke for an additional 20 minutes. Flip the ribs over and mop the other side with sauce.
Continue smoking the ribs until they reach an internal temperature of between 185°F and 190°F.
Remove the ribs to a clean cutting board and tent loosely with foil.
Allow them to rest for at least 5 minutes.
Serve with your favorite sides, such as grilled corn relish and biscuits.