Melt veal or beef fat in a cast iron frying pan. Sprinkle steaks with salt and pepper, then roll in flour. Add onion to pan, stir until well coated with fat, then cook over low heat 5-8 minutes, or until soft. Remove, pressing as much fat as possible, and set aside.
Add meat to fat in pan and brown lightly on both sides over medium heat. Top with onions and pour boiling water over it. Cover and simmer 30-40 minutes, turning meat once.
Then add sour cream, cover and simmer at a very low heat for 20 minutes -the meat will be tender and the gravy creamy.