Cut the meat into slices and beat a little with a hammer. Cut the onion into rings.
Fry the meat until golden brown in vegetable oil.
Add onion to the meat and sauté.
Pour in flour, mix well, pour in broth or just warm water, cover and simmer for 50 minutes. Then add spices, salt, mustard and sour cream. Stir and cook over low heat for another 30 minutes.
Serve the meat with a side dish sprinkled with herbs.