Preheat oven to 325F.
In a bowl, combine the smoked paprika, garlic powder, granulated onion, paprika, salt and pepper. Stir to incorporate.
Pat the ribs dry with paper towel and trim excess fat. Place the ribs meat-side down and use a paring knife to scrape off an edge of the membrane. Grab hold of the membrane with a piece of paper towel and slowly peel it back until it is all removed.
Generously season both sides of the ribs with the spice rub and massage to coat. Place the ribs, bone-side down, on a roasting pan lined with a wire rack. Cover the pan with a layer of parchment paper and tightly seal it with aluminum foil. Transfer the pan to the oven and roast until the meat is fork-tender and starts to peel back away from the bones, 1.5 to 2 hours, or more depending on the thickness of the ribs.
Remove the foil and parchment paper. Increase the heat to 375F. Brush both sides of the ribs with the BBQ sauce and return to the oven, bone-side down, and cook until the sauce has slightly caramelized, around 30 minutes. The ribs should be tender and easy to peel off the bone. If they are still firm, cover the pan with foil and return them to the oven, testing them every 30 minutes.
Brush the ribs with another layer of BBQ sauce before serving with the Dill Pickle Slaw.