Remove any fat and gristle from chuck roast; cut into strips ½-inch thick by 2-inches long. Season with ½ teaspoon salt and ½ teaspoon pepper.
Melt butter in a large skillet over medium heat. Add beef and brown quickly.
Push beef to one side of the skillet. Add onions; cook and stir for 3 to 5 minutes, then push to the side with beef.
Stir flour into pan juices on the empty side of the pan. Pour in beef broth and bring to a boil, stirring constantly. Reduce heat to low and stir in mustard. Cover and simmer until beef is tender, about 1 hour.
Five minutes before serving, stir in mushrooms, sour cream, and white wine. Cook until heated through; season with salt and pepper.
Enjoy served over hot cooked noodles.
