Tie the loin using kitchen string. Place all ingredients for the vegetable stock in a large pan and gently simmer.
Add the veal and cook making sure the core temperature does not exceed 65 °C.
The veal must be pink in the middle. Leave it to rest in the stock.
Tuna sauce
Put the tuna, mayonnaise, capers, anchovies and parsley in a bowl. Add the lemon juice and white wine and blend to a smooth creamy consistency.
Grana padano crouton
Heat a non-stick pan over moderate heat and sprinkle with the grated cheese. Pat down very lightly. When the cheese has melted and the edges begin to brown, use a silcone spatula to carefully remove the crisp wafer to rest on kitchen paper.
Herb and lemon seasoning
Put oil and lemon juice in a bowl with parsley and thyme. Mix well adding salt to taste.
To finish
Spread tuna sauce on plates and top with thinly sliced veal. Garnish with rocket, fennel and tomatoes.
Season with the dressing and garnish with cheese croutons and ground black pepper