Rinse the boiled beef and put it in a pot together with the veal stock, bay leaves, clove and peppercorns. Peel and add the onions. Bring to the boil, skim and let simmer at low heat for about 1 hour.
Peel, clean and rinse the celery and carrots. Clean the leek and rinse thoroughly. Cut vegetables into pieces or leek into strips as desired.
Remove the boiled beef from the stock and keep warm. Sieve the stock and put it back into the pot. Season to taste with salt. Cook the vegetables in the stock for about 10-15 minutes. Add the prunes in the last minutes.
Season again with salt and pepper.
Peel and finely grate the horseradish. Cut the boiled beef into slices and place in deep plates together with the vegetable stock and prunes. Serve sprinkled with horseradish. Serve with boiled potatoes.