Wash the cured pork and cut into cubes. Peel onions and cut into rings. Clean the savoy cabbage, cut out the stalk. Cut cabbage first into slices, then into large pieces. Blanch in 1/2 litre salt water, if necessary in portions, for about 3 minutes. Drain and store the cooking water.
For the puree boil 1/4 litre of water and milk. Remove the pot from the heat. Stir in the mashed potato flakes briefly. Stir again after 1 minute. Season with nutmeg and fill into an ovenproof dish. Fry onions and pork loin over high heat in hot oil while turning for about 3 minutes. Mix with savoy cabbage and spread on the puree. Melt the fat for the sauce. Sweat flour in it. Add cream and savoy cabbage stock while stirring constantly, bring to the boil. Season to taste with salt, pepper and mustard. Pour over the casserole.
Mix with savoy cabbage and spread on the puree. Melt the fat for the sauce. Sweat flour in it. Add cream and savoy cabbage stock while stirring constantly, bring to the boil. Season to taste with salt, pepper and mustard. Pour over the casserole. Bake in a preheated oven (electric: 200 °C/ gas: level 3) for 20-25 minutes. Serve sprinkled with fresh marjoram