Prepare the necessary ingredients for salting mackerel. Wash the fish carcasses with cold water and dry with a paper towel to remove excess moisture.
Cut the washed mackerel carcasses, remove the heads, fins and tails, clean the insides and rinse with water to remove any remaining entrails.
Start preparing the marinade; to do this, pour water into a saucepan, place it on the stove and bring the liquid to a boil. As the water boils, add salt, sugar and spices and boil the marinade for 5-7 minutes. When ready, remove from heat and set aside to cool.
While the marinade is cooling, cut the chopped mackerel carcasses into pieces of the same size, no more than 1.5 cm thick.
Place the chopped pieces of fish in a salting container, placing each piece of fish close to each other.
Pour the cooled marinade over the fish in the tray until it completely covers the mackerel. Add the spices recommended in the recipe to the marinade, cover the container with the fish in the marinade with a lid and put the dish in the refrigerator for 12 hours to salt.
Place lightly salted mackerel in brine with herbs and spices on a dish, add onions, finely chopped herbs and a side dish of mashed potatoes.