Peel and halve the onion and cut into strips. Grease a large ovenproof pan or a flat roasting pan. Spread the onion evenly in it. Wash the meat, dab dry and cut into 12 medallions (see picture below). Season with pepper on both sides, spread with mustard. Wrap 1 slice of bacon around each medallion and place on the onion. Cook the medallions in a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for approx. 30 minutes.
For the sauce, heat the cream and cream cheese while stirring. Wash and chop the parsley. Rinse peppercorns. Add both to the sauce. Pour over the medallions and continue cooking for about 10 minutes. Serve with tomato salad.
Cut the pork tenderloin into slices about 2 cm thick. This way round medallions are created.