Put the veal together with the vegetables in boiling water and cook for about an hour: it should still be slightly pink inside when you cut it open. Remove and sprinkle with vinegar while still hot. Leave to cool.
For the sauce:
Chop the tuna, together with the capers and the sour cream, crush it precisely.
Beat curd and olive oil with a whisk, mix well with the tuna puree, season with juice of one lemon and salt.
Cut the veal into fine slices. Arrange on a serving platter and baste with the sauce.
Garnish with capers and lemon slices if desired.
Tip: Do you know purple carrots? They are an old, very aromatic variety – why not use them for a change!