Wash the meat. Peel onions. Clean, wash and chop the carrots and leek. Put 1500 ml water, salt, peppercorns, bay leaves, onions, carrots and leek in a pot and bring to the boil.
Add the meat carefully and cook over a low to medium heat for about 1 hour. In the meantime, put eggs in boiling water and boil for 9 minutes until hard. Drain and quench. Remove the shell.
Finely dice eggs and cucumber. Pour the tuna fillets into a sieve, drain them, put them into a high mixing bowl and puree them. Stir in salad cream. Season with salt and pepper. Add half of the capers, 3/4 of the eggs and cucumber.
Remove the meat from the broth and allow to cool slightly. In the meantime wash the salad and drain well in a sieve. Cut the meat into thin slices. Line a plate with salad. Arrange the meat and some tuna cream on it.
Sprinkle with remaining capers, egg and cucumber cubes. Garnish with parsley as desired. Serve the rest of the tuna cream extra.