Note: Time for marinating!
The day before, clean and dice the onion and greens. Bring the stock to a boil. Add the vinegar. Add greens, onion, cloves, bay leaf, juniper and peppercorns and bring to a boil once.
Allow the marinade to cool.
Cut the meat into slices of about 150 g each, put them in a suitably sized baking dish, pour the marinade over them and marinate them for 24 hours with the lid closed, turning them once to the other side.
Remove the meat from the baking dish and dry it with kitchen roll. Drain the vegetables and spices in a colander, reserving the marinade.
Heat the clarified butter in a saucepan, brown the meat slices on both sides, season with salt and pepper. Add the greens and the spices and fry them as well. Pour the marinade.
Stew the meat for 1 hour with the lid closed.
In the meantime, for the dumplings, remove the peel from one third of the potatoes, dice them and make them in salted water for 20 min. After 15 min, remove the peel from the remaining potatoes, grate finely and squeeze heartily in a muslin cloth. Drain the cooked potatoes, steam them very well and press them through a potato press. Mix the raw and cooked potatoes in a baking bowl, add egg yolks and half of the cornstarch. Season the dough with salt, pepper and nutmeg and form into a roll, perhaps adding a little cornstarch.