Fry the chopped onion in a tablespoon of margarine and grind the tofu with a potato masher, add and fry until the tofu is a little dry and the color has changed a little. Put in a bowl.
Add the chopped sauerkraut, vegetable stock, caraway seeds, buckwheat, peppercorns, sugar and 1 teaspoon herb salt and mix everything to a firm dough. Season to taste with herb salt, form flat patties with wet hands and fry them in hot fat, turn down the heat, otherwise they will be too dark.