Rinse the meat and pat dry. Trim the leek, cut into small pieces and rinse well. Peel the carrot and onion and dice finely. In a non-corrosive bowl, mix together the wine, vegetables and bay leaf, add the meat turning to coat, cover and refrigerate overnight.
In a pan, bring the meat, marinade and enough water to cover to a boil, season with salt and simmer over low heat until cooked through, about 1 hour.
In a blender, puree the tuna with anchovies, egg yolk, 1 tablespoon capers, lemon juice and vinegar. Add the oil little by little, until the sauce is creamy. Season with salt and pepper. Thinly slice the meat and serve drizzled with the sauce and sprinkled with the remaining capers.
Serve as an appetizer.