Put the egg yolk, lemon juice, sugar and salt in a blender, mix briefly. Slowly mix in the oil while stirring until a thick mayonnaise is formed. Add the tuna, basil leaves and 2 tablespoons of capers, mix and mix with the juice of the tuna to a creamy sauce. To taste.
Cut the chicken breast into thin slices, arrange on a platter, cover generously with the sauce and sprinkle with the remaining capers. Let it go for a while.
For the blossoms, quarter the cherry tomatoes, but don`t cut through them, put a caper in the middle.