In a large pot, prepare a broth for the veal with vegetables (carrot, celery, onion), a bay leaf, and garlic. Add salt and pepper. Place the meat in the pot and cover it with water and white wine so that it is submerged.
Bring to a boil, then reduce the heat and simmer for about 2-3 hours until the meat is very tender. Let the meat cool completely in the cooking liquid.
Once cooled, remove the meat, pat it dry, and wrap it in plastic wrap. Refrigerate for at least 2 hours (ideally overnight). This will make it easier to slice thinly.
Using a blender or immersion blender, blend the drained tuna, mayonnaise, anchovies, capers, and lemon juice until a smooth, creamy sauce is formed.
To thin the sauce, you can add a little of the meat cooking liquid. Season with salt and pepper to taste.
Store the finished sauce in the refrigerator until ready to serve.
Slice the chilled meat very thinly. Arrange the slices on a plate and generously drizzle with the tuna sauce.
Garnish with capers (whole or chopped) and serve chilled. It is suitable as an appetizer or a light summer lunch.
