Preheat the oven to 240C/fan220C/gas 9 or its highest setting. Weigh the pork and calculate the cooking time at 20 minutes, plus 25 minutes per 450g. Use your fingertips to rub the vinegar and sea salt into the skin, making sure it gets into the score marks.
Roast on a rack in a roasting tin for 20 minutes. Reduce the oven temperature to 180C/fan160/gas 4. Roast the pork for your calculated cooking time: for this joint, cook for a further 1 hour 25 minutes or until cooked through. Pierce a skewer into the centre of the pork and check the juices run clear.
Set aside on a plate to rest, loosely covered with foil. Make the gravy. Drain the excess fat from the tin. Put the cooking juices in the tin over a medium heat and stir in the flour for 1 minute. Whisk in the Marsala and stock, then bring to the boil. Simmer for 5 minutes, until thickened slightly. Season and strain into a hot gravy boat. Meanwhile, cook the spinach. Heat the oil in a deep frying pan over a medium - high heat. Add the garlic and cook, stirring, until lightly browned.
Add half the spinach and cook briefly, stirring, until just wilted. Transfer to a colander to drain off the liquid. Repeat with the remaining spinach, then tip all of it into a bowl. Season to taste.
Thickly slice the pork and put on a serving platter. Drizzle with the gravy and spoon the spinach alongside.View more Pork recipes...