Clean and wash the leek, quarter lengthways and cut across into thin slices. Heat olive oil and butter in a pan, add the leek, wine and a small glass of water and season with salt and pepper. Cover and cook for 5 minutes.
Chop the meat and finely chop the parsley. Cut the mushrooms into slices. Put all the ingredients in the pan with the cream, mix, bring to the boil and simmer covered for 10 minutes.
Then season with lemon juice, salt and pepper and serve. Serve with rice or pasta.