- Heat oven to 150°C/fan 130°C. 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.
- 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.
STORAGE: these ribs will keep in the fridge for up to 3 days.