Select firm textured potatoes such as the Vitelotte type. Boil them in salted water and cut into thin slices whilst still warm; place in a basin and marinate with 3 dl (10 fl oz or 1¼ U.S. cups) dry white wine per 1 kg (2¼ lb) of potato. When ready to serve, mix very carefully with oil and vinegar dressing and some chopped chervil and parsley.