1Remove any fat and gristle from the roast and cut into strips 1/2 inch thick by 2 inches long. Season with 1/2 teaspoon of both salt and pepper.
2In a large skillet over medium heat, melt the butter and brown the beef strips quickly, then push the beef strips off to one side. Add the onions and cook slowly for 3 to 5 minutes, then push to the side with the beef strips.
3Stir the flour into the juices on the empty side of the pan. Pour in beef broth and bring to a boil, stirring constantly. Lower the heat and stir in mustard. Cover and simmer for 1 hour or until the meat is tender.
4Five minutes before serving, stir in the mushrooms, sour cream, and white wine. Heat briefly then salt and pepper to taste.
Footnotes
Tip
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.