Place the stock in an 8-quart saucepan and bring it to a simmer. Adjust the flavor and place the meat inside, making sure that will be completely submerged by the liquid. Place a lid on and cook gently without simmering (poaching is 190 degrees) until the meat reaches 110 degrees internal temperature. At that point turn the heat off and let the meat cool inside its own liquid. The carry over cooking should leave the meat medium and pink. (If you prefer it well done cook it longer).
Prepare the mayonnaise either by hand or in a food processor. Stir the egg yolks with salt, some lemon juice and add the oil very carefully. Adjust the flavor. Puree the tuna, anchovies and capers in a blender adjusting the consistency with some white wine, until smooth. In a bowl incorporate the tuna puree, the mayonnaise, the heavy cream, adjust the consistency and the flavor with more wine and vinegar as needed.
Place some of the sauce on a 12-inch plate. Slice the veal very thin and place it in the center of the plate on top of the sauce. Garnish with the celery, leaves, capers, anchovies, black pepper and extra-virgin.