How to cook
Wash the fish and remove the heads, gills, tails. Cut them into pieces. Make a brine from the salt and water.
To check the salinity, put a whole raw egg in the brine. If it rises up to the top, it means the water is well salted.
Put the cleaned pieces of fish in the brine for 10 hours. Then, discard the brine, pour vinegar over the fish and leave them to sit for another 10 hours.
Put the fish pieces in a cheesecloth to drain. Remove the skin membrane (if present), bones and spine.
Fry a bread slice in pan with heated oil (for it to get rid of the oil's smell). Arrange the fish pieces in a glass container - layer of fish, layer of dill and so on.