Finely chop the fish or turn the soaked, well-squeezed bun through the meat grinder. Stir in the diced onion, steamed in the fat, the liquid fat, the egg and, if you like, mustard and salt. As soon as a smooth mass has arisen, form dumplings out of it, turn them in breadcrumbs and fry them in the hot fat for approx. 6-8 minutes until golden brown.
The fish cakes serve with potato salad or boiled potatoes and vegetables.