- Heat oven to 150℃/fan 130℃. Combine the dry-rub ingredients in a small bowl. Arrange the rib racks in a single layer on a large chopping board or clean kitchen counter.
- Season with the dry-rub on both sides, patting it down into all the nooks and crannies. Double wrap the racks individually, first in greaseproof paper then with foil; seal into a tight parcel. Arrange the rib parcels in a single layer on one (or two) baking sheets and bake until the ribs are very tender but not quite falling apart, 2 ½ hours.
- Turn the oven up to 220℃. Line a large baking sheet with foil. Carefully unwrap the ribs. Using tongs, carefully transfer the rib racks to the foil-lined baking sheet, leaving the juices behind.
- Baste the ribs on both sides with half of the barbecue sauce. Roast uncovered for 10 minutes, turning once halfway through.
- Baste the ribs with the remaining barbecue sauce and roast uncovered for 6 to 8 minutes, turning once halfway through, until lacquered and starting to crisp. Transfer to a platter and serve.