Put the water in a large saucepan and add the onion, cloves, bay leaves, peppercorns and salt. Let everything boil.
Pour in the pork shoulder. Half cover the saucepan and simmer everything together for 70 to 90 min just at the boiling point. Towards the end of the cooking time, do the test: the meat should be nice and soft, then it is done.
Remove the shoulder roast from the cooking pot and cut into slices. Arrange on a heated platter and pour a little bit of cooking broth over it. Add the horseradish.
Serve with boiled potatoes accompanied by fresh bread. The beverage is a cool Pilsner.