Peel the onions and chop them finely. Clean the mushrooms and cut them into thin strips. Melt the butter in a frying pan and sauté the onions and mushrooms until soft. Dust with flour and douse with a little bit of clear soup. Season with pepper, mustard, salt and juice of a lemon. Cut the cucumber into thin sticks and add. Simmer this sauce for 10 minutes. Put the fillet briefly in the freezer form, so that it is easier to cut into strips. Season the strips of meat and fry them in a second frying pan in the butter for 5 to 6 minutes. Add them to the mushrooms and onions in the saucepan, season with the fresh cream and season repeatedly with the spices. It goes very well with a grainy cooked long grain rice with peas and a mixed leaf salad.
Tip: Cook only with high-quality spices – they are the be-all and end-all in a good dish!