3. Score the skin with a sharp knife to help the fat escape during cooking, but don’t cut all the way into the meat.
4. Pat skin dry then rub with salt and oil to help the fat render and the skin to puff and crisp.
5. Weigh joint and roast the meat for 25 mins at 240C, then turn the oven down to 190C and roast for 25 mins per 450g.
6. If you find that the crackling isn’t as crispy as you’d like near the end of the roasting time, turn the heat up and cook for a further 10-15 mins. Be careful not to overcook the meat though, as it will become dry.
7. Rest the meat for 10-15 mins before carving.