Sometimes called "the bouillabaisse of Hungary," Paprika Fish Soup is simplicity itself. It originated centuries ago with the fishermen who cooked it in big metal pots over campfires on the embankments of Hungary’s great rivers, including the Danube. In Hungary this fish soup often contains several kinds of local fresh fish—carp, catfish, sterlet, pike, perch, bream, whatever is available as the catch of the day.
2 pounds freshwater fish filets or 3 pounds whole freshwater fish (preferably a mixture of 2 or 3 kinds of fish)
2 medium onions, sliced into very thin rounds
3 tablespoons mild Hungarian paprika (or 2 tablespoons mild paprika and 1 tablespoon hot paprika)
2 to 3 crushed dried cherry peppers (or 1 to 2 tablespoons crushed dried red pepper flakes)
1 tablespoon salt
If using fish filets (fresh or frozen/thawed), wash them under cold water and set aside. If using whole fish, clean and eviscerate them, then cut the fish into 3-inch chunks. Save the heads and tails to add to the cooking pot for flavor.
Put a layer of sliced onions on the bottom of a large (6-quart) stockpot. Add a layer of fish and sprinkle it with some of the paprika, crushed cherry peppers or pepper flakes, and salt. Continue making layers of onion, fish, and spices until all of the ingredients are in the pot. Add enough cold water to barely cover the fish.
Bring the mixture to a boil over high heat, then reduce the heat to medium and let the soup simmer, uncovered, for 1 hour. Do not stir the soup during this time, but occasionally shake the pot gently from side to side. At the end of 1 hour, taste and add more salt if desired.
Serve hot, dividing the fish evenly among shallow soup bowls for each diner.