1. Preheat the oven to 230C.

2. Rub oil onto the skin, then sprinkle lightly with sea salt. Place on a rack in a roasting tin and add some water in the bottom. Place on the bottom shelf and roast for 30 minutes.

3. Reduce the oven temperature to 160C and cook for a further 1½ hours, or until meltingly tender. Turn off the oven, open the door and allow the pork to rest in the oven for 20 minutes.

4. For the sauce, boil the stock in a saucepan until reduced by half. Tip this out of the saucepan and reserve, then pour the cream into the saucepan. Slowly bring the cream to the boil, then add the reduced stock and mustard. Reduce slowly for 20 minutes. Add and adjust seasoning.

4. Place the pork on a chopping board and slip a knife under the crackling. Remove the crackling and chop into shards. Slice the meat. You will need to slice around the shoulder blade, but it is easy and you can end up with rustic slices, or chunks of meat.

5. Served carved meat and crackling at the table with a sauce boat of mustard cream sauce.

On roasting: A meat thermometer will also help to ensure all your roasts are cooked to perfection. For well done, the finished temperature should be 74 degrees. Take out the roast at 72 degrees, then let it rest. The residual heat in the joint will bring up the temperature. If you were cooking at high heat, say 200 degrees, you would pull the roast from the oven when it is 5 degrees less than the desired temperature. A rare roast is 55 degrees, medium is 62 degrees and well done is 74 degrees. Happy roasting.

On pork shoulder:
1. Ask your butcher to score the skin for you, or try using a craft knife; they are sharp enough to get through the skin, and you can set the blade so it doesn't cut too deeply.

2. Buy the pork the day before and leave in the fridge overnight, uncovered. It helps the skin dry out and promotes a great crackling.