Patterned Hamburger Sandwiches

Preparation:

Preparation: Prepare the tuna mousse and the green sauce, which will be used for the filling: place the softened butter in a bowl and work it into a cream with a wooden spoon, then add the tuna, well drained from the oil and chopped, a teaspoon of capers and an anchovy fillet, also drained from their respective preserve liquids and finely chopped. Mix everything until you get a smooth, homogeneous and frothy mixture. Flavor the mousse thus prepared with the juice of half a lemon and set aside. For the green sauce, finely chop the parsley with a hard-boiled egg yolk, two anchovy fillets, a gherkin and a teaspoon of capers rinsed under warm water. Place the minced meat in a bowl and mix in the breadcrumbs of a sandwich, softened with vinegar and squeezed, a pinch of salt and a glass of oil (minus two tablespoons). Mix with a wooden spoon until you get a smooth sauce, then set aside. Cook the burgers in a pan with two tablespoons of oil over moderate heat for 10 minutes, taking care to turn them a couple of times and season with the necessary salt and a grind of pepper. Cut the four sandwiches in half and stuff the first one with lettuce leaves, washed and dried, a tomato and a boiled egg, both cut into slices, a hamburger and a spoonful of salsa verde. Fill the second sandwich with slices of smoked bacon, a hamburger and radishes cut into thin slices. Fill the third bun with a hamburger and a layer of sliced raw onion, and the last one with a sliced tomato, a hamburger, a spoonful of tuna mousse and a fan-shaped gherkin. Bring the sandwiches to the table, serving what's left of the green sauce and tuna mousse separately.