1st for the sauerbraten: 1st place the beef in the buttermilk with the peeled onions, juniper berries and pepper, cover and let stand for 4 days (turn once in between)
When the roast is ready to pull, take it out of the refrigerator, remove it from the marinade and pat it dry. Save the marinade and sift out the juniper berries. Peel the carrot and cut into large pieces.
Heat the roast fat in a large pan or roasting pan, fry the roast with the bread crust and carrot all around, so that there is a nice roasting set. Season with salt, pepper and paprika. Deglaze with 200 ml of water. After 15 minutes, carefully drizzle the meat with the vinegar (all around) Then add 250 ml of the stain. When the liquid is simmered, refill a little. This can be done 1-2 more times (but max. 500ml in total), then fill up with another 500 ml of water. Slowly simmer the roast in the closed roaster or in the pan with a lid for about 1 1/2 hours. Finally stir in the grated sauce cake, add sugar to taste, done.
for the red cabbage: cut the red cabbage into strips without the stalk. Put the cabbage in a large saucepan and add the water. Add the butter, vinegar, salt and sugar and let cook. Finally, taste whether something else needs to be added.
for the dumplings: Boil the potatoes in the water, drain them when they are done and let them cool down a little, then peel them. Press the peeled potatoes in the potato press and cover with a kitchen towel and leave to cool. (Cooking and pressing can also be done the day before)
Cut the white bread into small cubes, toast in the margarine or butter and let cool.
Mix the cold potato mixture with the egg, the flour, 40 grams of cornstarch and season with salt and nutmeg. Put on a large saucepan with salted water and bring to a boil. Shape the mixture into 10 dumplings and place 2 pieces of toast bread cubes in the middle. Roll the dumplings in the rest of the cornstarch and leave them to rest so they don't stick to the surface. Put the dumplings one after the other in the water and reduce the temperature, it must no longer boil, let it steep for 20 minutes.