For the potato dough, first put a pot of water on the stove and bring it to a boil.
Cook the 800 g starchy potatoes in it with their skins on until done, about 20 min.
Meanwhile, prepare the filling. To do this, cut the rind off the 150 g pork belly bacon and remove the casing from 1 Kohlwurst / Mettenden / Krakauer sausage.
Cut all the meat, including the 300 g Kassler (smoked pork loin), into small pieces and ideally put it through a meat grinder. If you don't have one, or if, like me, you find it too much effort, you can also use an electric chopper. In that case, chop the meat in small portions only briefly so that you get a crumbly filling (see also Tips & Tricks).
Finely dice 1 onion and 1 garlic clove and sauté in a pan over medium heat until soft.
Let the onions cool, add them to the meat filling and season with 0.5 tsp marjoram and 1 pinch each of salt and pepper.
As soon as the potatoes are done, drain them and let them cool briefly on a towel for about 5 min.
Meanwhile, shape about 12 small balls from the meat mixture. Don't press the balls together too firmly, because the filling shouldn't turn into a lumpy mass.
Peel the potatoes while still warm and press them through a potato ricer (see Tips & Tricks).
Add 200 g coarse (double-grip) flour, 30 g durum wheat semolina, 1 egg, 1 egg yolk as well as 0.5 tsp salt and 1 pinch nutmeg to the potatoes.
Quickly knead the ingredients with your hands into a smooth dough and shape it into a thick log. Add a little more flour if needed.
Let the dough rest briefly, covered (see Tips & Tricks), and then cut it into 12 equal pieces.
At the same time, put a large pot of salted water on the stove and bring it to a boil (see Tips & Tricks).
Have some regular flour ready and shape the individual pieces into flat circles. Lightly flour the top and bottom and place one of the prepared meat balls on each. Carefully wrap the dough around it and gently shape into dumplings (see Tips & Tricks).
Lightly flour the finished dumplings once more and set them aside until cooking.
Depending on the size of the pot, add about 6 - 8 dumplings to the boiling water and let them cook through in gently simmering water without a lid (!) for about 20 min (see Tips & Tricks). Carefully cover the remaining dumplings.
While the dumplings are finishing, you can prepare the sides. They taste best with boiled or fried sauerkraut with onions and diced bacon as well as a tasty gravy.
The dumplings are done when they float to the surface. If you want to cook the remaining dumplings right away, you can keep the finished ones warm in a covered pot in the oven at 100 °C (212 °F).