Bring ox leg and bones to boil with 2 1/2l cold water and skim.
Cut the unpeeled onions diagonally in half, roast the cut surfaces until brown. Rinse, clean and coarsely chop greens. Add the onions, greens, spices and a little salt to the saucepan and let the whole thing steep rather than make in about 2 hours in an open saucepan.
Cut the liver into strips. Coarsely dice the bread. Pluck thyme from stems.
Fry a good half of the thyme and the rolls in the fat, cool a tiny bit. Now alternate with the liver strips through the fine disc of the meat grinder.
Stir the mixture with the egg, season vigorously with salt and pepper and leave to cool.
Pour clear soup through a hair sieve, skim off excess fat and season the clear soup.
Rinse carrots, remove peel and cut into thin slices. Peel the white onion and cut into thin slices. Add both to the clear soup with the remaining thyme and simmer for 20 minutes.
Form 16-20 liver dumplings with two damp tablespoons, cook in boiling salted water for 20 min, lift out with a slotted spoon, steep in the clear soup for another 5 min.