Cook the pasta in boiling salted water for about 8 minutes. In the meantime, clean, wash and halve the mushrooms for the sauce. Clean, wash and cut the leek into rings. Wash cutlets, dab dry, dice.
Heat the oil. Fry the escalopes in it until golden brown while turning, remove. Melt the fat in the pan. Fry the mushrooms well, season with salt and pepper. Add leek. Deglaze with 200 ml water and cream, add meat cubes again and bring to the boil briefly.
Season to taste with salt, pepper and mustard. Add the sauce thickener, bring to the boil briefly and serve with the pasta. Serve garnished with fresh herbs as desired.