Directions

1. Heat the oil in a saucepan and cook the onion for 5 mins until soft. Remove from the heat. Once cool, transfer to a bowl and mix in sage, breadcrumbs, sausage meat and some seasoning.
2. Untie the pork and score the skin well with a sharp knife. Cut down the length of the meat, then open out like a book so you can stuff the sausage meat inside. Close back up to resemble original shape and tie at intervals with string to hold it together. Weigh so you know how long it will need to cook for. This can be done ahead; chill until needed.
3. Heat oven to 240C/220C fan/gas 9. Rub the joint all over with salt and pepper and place in a roasting tray. Cook for 25 mins, then turn to 180C/160C fan/gas 4 and cook for 20 mins per 450g/1lb. Remove, and check it's cooked through: any juices that run out should be clear. Transfer to a dish, then cover with foil to rest while you make the gravy.
4. Spoon most of the fat out the tray, leaving the meat juices. Place tray on the hob or transfer juices to a frying pan. Stir in the flour for 1 min followed by the stock and cider, and bubble for a few mins. Strain into a jug. Serve the pork sliced, with the crackling, potatoes, gravy and veg.