Put the water, sugar, salt and vinegar in a small saucepan and bring to the boil. After boiling, add the oil and pepper and pour the mixture over the onions while they are still hot, so that they lose their sharp taste.
When the marinade has cooled down, place the smoked pork with the onions in the marinade, slice by slice, so that all slices are covered with marinade.
It is best to leave the onion meat in the refrigerator overnight.