Peel, core and dice the cucumber. Also clean and dice peppers, mushrooms and onions.
Fry the onions and mince in the hot oil for about 5 minutes. Add paprika, mushrooms, cucumber and onions and fry for another 5 minutes, then season. Pour in the broth and simmer for about 10 minutes. Stir in the crème légère and mustard, season to taste and, if necessary, add seasoning.