Preheat the oven to 90 degrees. Pour the olive oil and sunflower oil together in a large pan and heat to 190 ° C.
Place 1 slice of bread on the work surface and place 2 slices of mozzarella on top, then cover with another slice of bread. Repeat until the mozzarella and bread are used up. Cut off the crust so that it forms an even square or rectangle. Stick a kebab skewer in the middle for hold. Cut off excess.
Put the eggs, milk, salt and pepper in a long, flat bowl and mix well. Mix eggs, milk, salt and pepper. Roll the bread and mozzarella stack in the flour and shake off any excess. Soak in the egg mixture briefly on each side and then fry in the hot oil on each side until golden brown. Then place on a double kitchen towel and remove the kebab skewer and, if necessary, place in the preheated oven to keep it warm.
For the sauce: Heat the remaining 2 teaspoons of olive oil in a saucepan on medium heat. Add the garlic very finely chopped and fry until golden. Add the sardine fillets. Continue frying, stirring, until the fillets disintegrate almost completely. Add white wine, lemon juice and capers and keep stirring. Bring to the boil briefly and then continue to simmer until the sauce is reduced by half. Finally stir the chopped parsley into the sauce.
Then cut the bread into slices with a sharp knife and spread the sauce over the top. Garnish with sprigs of parsley at last.