Fill a large pot with about 750ml ofwater and add the vinegar, a large pinch of salt, peppercorns, bay leaf and the coarsely chopped onion. Bring to boil, let it boil vigorously for about 5 minutes. Reduce the heat and put the carp fillets in the water. Depending on size, simmer for about 8–10 minutes. Remove, and keep warm. Drain the stock, and set aside.
For the sauce, heat the butter in a pan. On reduced heat, fry the gingerbread crumbs, nuts, almonds, raisins and prunes. Stir in the honey. Spoon in some of the fish stock until the sauce is thick. Pour in the beer and let simmer until the sauce is thick and creamy. Add optional powidl.
Put the carp fillets back in the sauce, turning them over once. Warm them up in the sauce on low heat.