Remove the cabbage leaves from the head and boil in salted water. Lay 2 sheets on top of each other. Soak the bun and squeeze it out. Work the mince with the bread roll, mustard and a little salt and pepper into a meat dough and fill the leaves with it. Press firmly all around and tie with a thread. Fry them well on all sides in the hot clarified butter and let simmer for 1 hour.
Thicken the resulting sauce with 1 cup of sour cream and a little flour. I recommend boiled potatoes as a side dish.