Prepare the brine. Mix the brown sugar and salt in the cold water and add the pork chops. Keep refrigerated overnight, discard brine and start preparation for the stuffing. Cook the sausage meat with the onions until slightly browned, grate the apple and stir in. Add a splash of cider and bind with the bread crumbs. Sprinkle with some chopped parsley. With a small sharp knife cut a pocket in each of the pork chops, taking care not to cut through the meat; push as much stuffing as possible. Melt the butter in a frying pan with the garlic clove and thyme. Seal the pork chops in the hot fat, sprinkle with fennel seeds and deglaze with the cider. Transfer the meat to a baking tray and cook for approx. 15 minutes in a hot oven. Spoon the grain mustard in the same frying pan and start reducing with enough chicken stock to obtain a slightly dense sauce. Simmer the fennel with some cider, season well and stir in the lentils. Spoon the lentils in the centre of a large serving plate. Lay the pork chops on top and spoon over the grain mustard sauce.