01 - Remove the thin membrane from the back of each rib rack using a paper towel for grip. This step ensures better spice penetration and tender results.
02 - Combine brown sugar, paprika, smoked paprika, garlic powder, onion powder, black pepper, salt, and cayenne pepper in a small bowl. Mix thoroughly until evenly distributed.
03 - Rub the spice mixture generously over both sides of each rib rack, pressing firmly to adhere. Let seasoned ribs rest at room temperature for 20 minutes to allow flavors to penetrate.
04 - Prepare charcoal or gas grill for medium indirect heat, maintaining temperature between 285°F and 320°F. Arrange coals to one side or turn off center burners for indirect cooking zone.
05 - Place each rib rack on a large sheet of heavy-duty aluminum foil. Add 1 tablespoon apple cider vinegar to each packet, then seal tightly, crimping edges to lock in moisture.
06 - Position foil-wrapped ribs on the indirect heat side of the grill. Cover and cook for 1½ hours, turning packets every 30 minutes for even heat distribution.
07 - Carefully open foil packets (watch for steam). Remove ribs and brush both sides generously with barbecue sauce, reserving some sauce for final glazing.
08 - Return ribs directly to grill over medium heat. Grill uncovered for 10 to 15 minutes, turning every few minutes and basting with remaining barbecue sauce until glaze is caramelized and slightly charred.
09 - Transfer ribs to cutting board and let rest for 5 minutes before slicing between bones. Serve immediately with additional barbecue sauce on the side.