Peel and roughly chop the carrots, celery, onions and garlic. Boil the vegetables and about 2 litres of water in a tall narrow pot. Season with salt, peppercorns, laurel and cloves. Dab the meat dry, put it into the pot and bring the stock to boil.
Cook the meat in the boiling broth for about 2 hours. Leave meat to cool in the broth.
For the sauce puree tuna with brine, 2 tbsp. capers, anchovy fillets, salad mayonnaise, vinegar, white wine and cream very finely. Season to taste with salt, pepper and sugar.
Wash parsley, shake dry, pluck leaves from the stalks and chop. Cut lemon into slices. Remove meat from the stock, dab dry and cut into thin slices. Serve meat and sauce with lemon wedges.
Sprinkle with parsley and capers.