Tenderize beef cutlets. Salt and pepper both sides and brush with tarragon mustard. Flour.
Melt butter in pan and sear beef cutlets with floured side.
Turn, sear briefly, remove meat and set aside.
Sauté onion and caper berries in the drippings, stir in remaining flour with beef broth.
Add the beef cutlets to the pan and finish cooking on low heat for about 45 minutes.
Serve with spaetzle. If you don't like capers, make the beef cutlets without.