For the onion meat, cut the beef into flakes. Heat butter in a pan and fry onion in it.
Deglaze with vinegar, add beef, roast briefly and pour in beef broth. Season with salt, thyme, marjoram and lemon.
Stew meat for about half an hour until tender, adding beef broth constantly, then dust with flour and cook thoroughly.
Arrange the onion meat and serve.