The fish is thawed and crushed by hand until the mess. Fry the finely chopped onion in the oil a few minutes, add the fish and mash 1 cup water and stir constantly until it boils. Maha from heat and add flour. Season with pepper and salt and mix. Add eggs one at a time, stirring to obtain a homogeneous mixture. In small ice trays (I use of chocolates) put the mixture (much easier with a syringe) and trays left at least one night in the refrigerator. Of sheet for banitsa cut squares so great that by putting a cube of fish, can be folded nice envelope. So shaped bags are fried in hot fat, first fry with folded edges down. Serve warm.