Clean the bonito, cut the head off and remove the viscera. Add salt. Fry the grated onion in 2-3 tablespoons of butter. Add the chopped hard-boiled eggs, semolina, which has been pre-boiled in water, salt and pepper.
Fill the fish with this stuffing, roll it in the flour and put it in an oven dish with 2-3 tablespoons of oil. Bake for 8-10 minutes. Add 1 cup of cream and leave in the oven for a while.