Place one rib rack meat-side down on your cutting board. Using a sharp knife or your fingers, peel away the thin, silvery membrane on the underside of the ribs.

Flip the ribs over and trim any dangling meat or excess fat from the edges.

In a small bowl, combine the brown sugar, paprika, garlic powder, onion powder, black pepper, salt, and cayenne pepper. Stir well to break up any brown sugar clumps.

Pat both sides of the ribs dry with paper towels, then generously coat every surface with the dry rub, using your fingers to press it firmly into the meat.

Heat your grill to 225 to 250 degrees Fahrenheit using an indirect cooking setup: if using charcoal, push coals to one side and place ribs on the opposite side; if using gas, heat only one or two burners and place ribs on the unheated side.

Place the rubbed ribs bone-side down on the cool side of the grill, close the lid, and cook for 2 hours without opening the grill frequently.

After 2 hours, carefully wrap each rib rack tightly in aluminum foil or butcher paper, then return them to the grill for another 45 minutes to 1 hour.

Mix the barbecue sauce, apple cider vinegar, Worcestershire sauce, and melted butter in a small bowl, then unwrap the ribs and brush this glaze generously over both sides.

Return the unwrapped ribs to the grill for the final 15 to 20 minutes, turning and brushing with glaze every 5 minutes until the sauce caramelizes into a glossy, sticky layer.

Transfer the ribs to a cutting board and let them rest for 5 minutes before slicing between the bones.