Finely scrape the liver with a sharp knife on the cutting board (do not cut it, otherwise it will be watery).
Lightly fry the finely chopped onion in butter, mix with the parsley and stir thoroughly in a bowl together with the well-squeezed rolls and the liver.
Strain the resulting mixture through a float or wire sieve. Add the egg, butter and breadcrumbs, season with salt, pepper and marjoram. Mix well again and let the mixture rest in a cool place for about 1/2 hour.
With slightly moistened hands, form small dumplings from the mixture and boil in lightly simmering salted water until they rise after about 7 minutes. To be on the safe side, cook a test dumpling first and add a little more breadcrumbs to the dumpling mixture to bind it if necessary. Let the dumplings stand for about 5 minutes in hot, but no longer boiling water.
Place the cooked dumplings in a soup plate and pour hot beef broth over them.