Salisbury Steak with Mushroom Gravy

Ingredients:

1 10.5 ounce can condensed French onion soup
1 1/2 pounds ground beef
1/2 cup dry bread crumbs
1 egg
1/8 teaspoon ground black pepper
1 tablespoon all-purpose flour
1/4 cup ketchup
1/4 cup water
1/2 teaspoon mustard powder
1 ounce package fresh mushrooms, sliced

Directions: 

1. In a large bowl, mix together 1/3 cup condensed French onion soup with ground beef, bread crumbs, egg, salt and black pepper. Shape into 6 oval patties.
2. In a large skillet over medium-high heat, brown both sides of patties. Pour off excess fat.
3. In a small bowl, blend flour and remaining soup until smooth. Mix in ketchup, water, mustard powder and mushrooms. Pour over meat in skillet. Cover, and cook for 20 minutes, stirring occasionally.