Stick the cloves in the onion. Fill a stock pot with water, add carrot, celery, onion, tomato, salt and pepper. Bring to boil and add the veal. Cook for approx. one and half to two hours, or until the meat will be tender. Remove the meat and cool at room temperature. Place the meat in the refrigerator 3 - 4 hours. Filter the broth and reserve for a different preparation.
In a food processor put tuna fish, anchovies, capers, lemon juice, oil, and run the blade to reduce to a very fine and smooth paste. If the sauce is too dense add 2 - 3 tbl.spn. broth to obtain the right consistency. Transfer the mix to a bowl, stir in the mayonnaise, and mix until obtaining an homogeneous paste.
Cut the meat in thin slices, place in a serving place, and cover with the sauce. The preparation can be kept in the refrigerator overnight if necessary. Garnish with lemon slices, capers, parsley just before serving.