For the filling, chop the kale. Heat lard in a saucepan, add kale and sauté briefly, pour in clear soup, season with salt and season with pepper. Cover and cook on medium heat for 6-8 minutes. Add the grated potato to the kale, fold in well, heat everything together again so that the potato starch binds. Cool the cabbage. Form 20 small balls from 1 heaped tbsp of kale at a time. (For the sauce, cut the bacon diagonally into small strips.
Peel onions and cut into thin strips. Fry bacon with oil in a saucepan over medium heat and lift out of fat. Sauté onion slices in bacon fat until translucent, add 250 ml water, fold in both types of mustard and bring to a boil once briefly.
Add the bacon strips to the sauce and pour in the red wine.
Heat the sauce before serving, perhaps add more salt.
For the dumplings, cook the peeled potatoes until tender. Peel as hot as possible and press through potato ricer. Add flour, cornstarch and egg, season with salt and nutmeg and knead into a smooth dough, divide dough in half. Sprinkle the surface lightly with flour or semolina and form 2 dough rolls, each 30 cm long. Divide each roll into 10 evenly sized pieces.
Form the dough pieces into balls with your hands, place them on the dusted surface and flatten them slightly. Fold into the center