Heat the butter, add the onion and cook until it has just softened but not browned. Add the green pepper and paprika and cook on a low heat for 3 minutes. Add the mushrooms, stir well and cook for a further 5 minutes until they are soft. Stir in the sour cream, season to taste and warm through gently.

Serve, sprinkled with parsley, as on hors d'oeuvre with hot French bread, as a filling for vol-au-vent, on fried bread or with a crisp salad.