Pink foam of hake

Preparation:

Preparation: Brown the chopped shallot in a pan with two spoonfuls of oil, then add the tomato concentrate and the hake. Cook for a quarter of an hour, salt and pepper. Then blend the hake with their sauce, add the sherry and ricotta and blend again. Meanwhile, soak the isinglass and then dissolve it in a few spoonfuls of warm white wine. Add it to the blended fish, flavored with grated lemon zest and lastly incorporate the egg whites until stiff, mixing gently. Pour the mousse into a fish-shaped mold and place in the refrigerator to cool. Serve the mousse, turning it out onto a plate and decorating it with lemon slices.