Fry the meat in oil in portions on each side for approx. 2 minutes. Season with salt and pepper. Sweat the onions in the frying fat, season. Mix the garlic with the crème fraiche, cream and ketchup.
Layer the pork tenderloin and smoked bellies alternately in a dish. Spread the onions on top and pour the sauce over them. Bake in the oven preheated to 175 ° C for about 30 minutes.