Put onions in a food processor, using course blade.
Drain and collect and reserve juice. There should be 3 cups of onion.
Fry slowly for 20 minutes. Then cut round steak into very thin slices.
Add in the beef and sliced mushroom and stir cook until brown.
Combine tomato soup, tomato paste, onion juice, sour cream, salt, pepper and Worcestershire sauce.
Pour the mixture on the beef, then cover and simmer for at least 1 hour. Serve hot.