Remove the pork from the fridge 1 hour before cooking to allow it to come to room temperature.

Preheat the oven to 240°C/Fan 220°C/475°F.

If the pork has not already been scored by a butcher, use a very sharp knife to score the skin (this allows the fat to escape during the cooking process). Brush all over with the oil and season well with sea salt. Place the sliced onions in a roasting tin and place the pork on top (make sure the onions are tucked underneath the meat).

Roast for 25 minutes, then reduce the temperature to 190°C/Fan 170°C/375°F and roast for another 25 minutes per 500g until the skin is really crispy. Remove the pork from the oven, transfer to a board and cover loosely in foil.

Meanwhile, cook the cabbage. Melt the butter in a heavy-based saucepan and fry the onions for 5 minutes over a medium heat until softened. Add the apples and cook for 3–4 minutes, then stir in the cabbage, sultanas, sugar, vinegar and stock. Bring to a simmer, cover with a lid and cook gently for 15–20 minutes, until the cabbage is softened. Remove the lid and turn up the heat until most of the liquid has evaporated. Remove from the heat, replace the lid and keep warm.

To make the apple sauce, place the apples and 4 tablespoons water in a small saucepan and cook over a medium heat for 10–15 minutes until the apples have softened. Using a stick blender, puree to make a smooth sauce. Set aside.

To make the gravy, strain the roasted onions from the tin, reserving 3 tablespoons of the cooking fat. Press the cooked onions through a sieve into a saucepan. Add the reserved fat and place over a medium heat. Stir in the flour and cider and bring to the boil. Cook for 5 minutes, stirring, until the sauce is thickened. Season to taste.

To carve the pork, cut away and discard the string. Using a pair of kitchen scissors, cut through the crackling so the meat is easier to access. Cut the pork into thickish slices and serve with the braised cabbage, apple sauce, gravy and potatoes of your choice.