Make the mayonnaise. Beat the egg yolk with a hand blander for a minute until sticky and thick. Add a tablespoon of lemon juice or white vinegar and a pinch of salt and beat for a further 30 seconds. The yolks are now ready to receive the olive oil slowly. Pour it in a thin stream, or add it drop by drop, and do not stop beating until the mayonnaise has thickened. Add mustard, lemon juice, salt and pepper to taste. Finish with the chopped parsley and chives.

Now cook the beetroots: peel it and cut it into thin slices. Dust with flour each slice and fry them in a large pan with some olive oil. Cook them for a few minutes, until crisp on the edges and soft inside.

Leave them to dry for a few minutes on a sheet of paper towel and sprinkle with a pinch of Maldon salt.

Cut out the squares of schiacciata, spread both sides with the herb mayonnaise and arrange the cooked ham on one slice and the beetroot chips on the other.

Close the sandwich and wrap it in kitchen paper, then in an aluminum foil, to keep it fresh.