Boil potatoes in salted water until tender, peel them and allow to cool down. Then cut potatoes into slices and dice onion. Cut cold meat into small peaces and if you use escalopes, cut them into stripes.
Fry onion, add potatoe slices until golden brown. Season to taste with marjoram, salt and pepper. In another pan fry cold meat or escalope stripes. Season with salt.
Mix well meat and potatoes, season and sprinkle with parsley.