Trim the meat.
Tie with kitchen string to a keep in shape.
Peel the carrots and onions.
Wash the leeks and celery.
Cut everything roughly into pieces
Place the vegetables in a large pan and cover with the stock and wine. Bring to the boil. Add the bay leaves, pepper and juniper and add the meat, making sure it is covered. Cook for 2 hours just below boiling point. Top up with stock or water as needed. Leave to cool overnight.
Remove the meat and cut off the kitchen string
Pass the stock through a sieve.
Cut the meat into thin slices.
Drain the tuna in a sieve.
Pat the anchovies dry.
Mix the anchovies with the tuna in a blender.
Add the yolks, about 100ml veal stock and blitz.
Gradually add the oil until a creamy sauce is formed. Add some stock if necessary.
Season with lemon juice, salt and pepper.
Place the meat on a plate with the lemon slices, pour over some sauce and serve the rest separately. Scatter the drained capers over and serve garnished with mint.