Place some clarified butter into a pan on high heat. Add the onions and allow to fry for 2 minutes until golden brown. Add the meat, season with salt and black pepper and allow to fry gently for 5 minutes. Stir in the flour and cook for 1 minute. Add the catsup combined with the Worcestershire sauce and then stir in the sour cream. Allow the Stroganov to simmer for 4 minutes. Serve accompanied with French fried potatoes, if desired.