Fry the roast pork in clarified butter until browned all over. Then season as needed and pour in some broth (do not salt too much, as the broth also contains salt).
Peel four onions, cut into rings and add to the meat. Check again and again whether there is still enough liquid in the roasting pan / saucepan, otherwise add some of the broth. Let the whole thing stew for about 1 1/2 hours. Then cut the fifth onion and add it to the sauce. A good, creamy sauce should have formed. Finally, remove the meat and stir about half a cup of sour cream into the sauce.
Tip: If it is a little too salty, you can also use the whole cup.
The amount of broth can vary a bit, depending on how quickly the sauce boils down. So it`s better to check it out more often.