Simmer shallots, carrot, celery, herbs, wine, and stock in a pan for 30 minutes.
Trim the veal and lower it into the simmering stock.
Poach the veal for 15 minutes, turning 4 to 5 times.
Reserve 100ml of cooking liquid and set the veal aside to cool.
Season the cool veal with pepper, wrap in film, and chill overnight.
Process egg yolks, tuna, capers, lemon juice, mustard, and sugar until combined.
Slowly drip in both oils while blending to emulsify into a thick mayonnaise.
Thin the sauce with 30ml of reserved cooking liquor and chill overnight.
Slice the chilled veal thinly and arrange on plates.
Top with tuna sauce, capers, parsley, and caper berries before serving.