Bring vinegar and 1 litre of water to the boil. Add 1/2 teaspoon salt and cucumber spice. Wash the meat and put it in the stock. Cover and cook over medium heat for 40-45 minutes. In the meantime, peel and wash carrots and cut them into slices with a colored knife.
Peel onions and cut them into thin rings. Add carrots, onions and bay leaves to the meat 10 minutes before the end of the cooking time. Remove the meat. Pour the stock through a sieve and chill. Keep onions, carrots and spices.
Cut the meat into large pieces. Cut cucumbers into slices. Place meat, cucumber, carrots, onions and bay leaves in a bowl. Soak gelatine in plenty of cold water for about 10 minutes.
Skim the fat from the brew. Heat the brew. Season to taste with salt, pepper, sugar and possibly vinegar. Squeeze the gelatine and dissolve in the stock. Pour the liquid carefully over the meat. Let sour meat get firm overnight.
Wash the potatoes and bring to the boil covered with water. Cover and cook for 20 minutes. Drain potatoes, rinse and skin. Let potatoes cool down and cut into slices. Heat oil in a pan.
Fry the potatoes until crispy. Season with salt and pepper. Wash and drain the lettuce leaves. Arrange the sour meat on a salad leaf and the potatoes on plates. Garnish with parsley.
Remoulade sauce tastes good with it.