1. Heat oven to 150°C/fan 130°C. Season the ribs with 1 tsp sea salt and couple of cracks of freshly-ground black pepper.
2. Arrange the racks in a single layer in a large roasting tin. Pour the coca-cola over the ribs, tightly cover the roasting tin with 2 layers of foil and bake until the ribs are very tender but not falling apart, 2 to 3 hours.
3. Combine the barbecue sauce and sweet chilli in a bowl and season with a pinch of sea salt and freshly-ground black pepper; set aside.
4. Once cooked, carefully transfer the ribs to a baking sheet. Turn the oven up to 220°c / fan 200°c. Drain and clean out the roasting tin, then line it with foil.
5. Return the ribs to the foil-lined roasting tin. Baste the ribs on both sides with half of the sticky sauce. Roast uncovered for 10 minutes, turning once halfway through. Baste the ribs with the remaining sticky 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.