Heat the oven to 220°C (425°F) gas 7. Wipe the meat with a clean damp cloth, then generously sprinkle the surface with salt, freshly ground black pepper and crumbled fresh rosemary and thyme and rub in with your fingers. Place the meat, fat side up, on a rack in a roasting tin. Roast in the oven for about 1 hour or until the pork is half cooked, basting occasionally.

Meanwhile, peel and thinly slice the potatoes. Pour the milk into a large, heavy-based saucepan, add 275 ml (10 fl oz) water and bring slowly to simmering point. Add the sliced potatoes to the pan and simmer for 10 minutes or until half cooked, then drain.

Select a shallow oval or rectangular gratin dish (preferably flameproof) which is large enough to hold the pork. Combine the drained potatoes with the chopped onion and parsley and spread over the base of the dish. Season to taste with salt and black pepper and spread with the softened butter. Remove the pork and reduce the oven temperature to 200°C (400°F) gas 6.

Place the pork on top of the vegetables in the gratin dish and pour in the hot stock or water. Set the dish on a protective asbestos mat over medium heat and bring the liquid to the boil. Then carefully transfer the dish to the oven. Cook for a further 30 - 40 minutes, or until the meat juices run clear when the meat is pierced with a skewer, almost all the liquid has cooked away and the potatoes are tender. Garnish with cutlet frills and serve.