Peel and wash the potatoes, cut them into cubes and boil them once in boiling salted water. Pour onto a sieve and drain. Soak rolls in cold water. Wash pork belly and ham, dab dry and dice finely.
Press the sausage meat out of the skin. Squeeze the bread roll. Knead well with pork belly, ham, sausage meat and eggs. Mix in the potatoes and season to taste with salt, pepper, nutmeg and marjoram.
Fill stomach with the mixture (not too bulging, but without air pockets!). Close tightly with kitchen string. Wrap stomach firmly in a tea towel so that it does not burst. Boil water in a large pot.
Place the stuffed pig's stomach in it and simmer for about 2 1/2 hours. Remove the stuffed pig's stomach from the pot, wrap it from the tea towel and brush it with 2 tablespoons of butter. Let it cool down. Cut the stuffed pig's stomach into thick slices.
Melt 3 tablespoons of butter in a frying pan. Briefly fry the slices on both sides in portions. Arrange stuffed pig's stomach on plates. Roast potatoes and sauerkraut are delicious with it.