Remove any fat and gristle from chuck roast; cut into strips 1/2-inch thick by 2-inches long. Season with 1/2 teaspoon salt and 1/2 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.