For the veal in tuna sauce, place the veal, water, white wine, bay leaves, peppercorns and salt in an unperforated cooking container.
Peel carrots and cut into pieces. Peel and halve onion and add to meat along with carrots and cook. (at 100°C 60-80 minutes or at 120°C 30-40 minutes).
Drain tuna and puree with oil, egg yolk and capers in a blender. Add lemon juice and stir in oil drop by drop until sauce has the consistency of mayonnaise. Season to taste with salt and pepper.
Thinly slice the cooked meat against the direction of travel of the meat fibers and arrange on a platter. Pour the sauce over it and garnish with capers and lemon slices. Fresh white bread is recommended as a garnish.