Soak 100g of dried mushrooms in water, then boil them and drain in a colander.
Cut 1 kilogram of fish into pieces, remove the bones, and sauté until golden brown.
In a saucepan, bring half a kilogram of onions to a boil in a cup of oil, then add a tablespoon of flour, pepper, and salt, and remove from heat.
In a Dutch oven, layer the fish, onions, and mushrooms, then place it in the oven at a moderate temperature for one and a half hours.