In a large bowl, beat egg. Stir in 1/3 cup of soup, bread crumbs, salt and pepper. Add beef; mix gently. Shape into 6 oval patties.
Brown in a skillet over medium heat for 3-4 minutes on each side. Remove and set aside; discard drippings. In the skillet, combine flour and water until smooth;
add the ketchup, worcestershire sauce, mustard and remaining soup; bring to a boil. Cook and stir for 2 minutes until thickened.
To Freeze: Freeze patties separate of the sauce or they will become too salty. Do not prepare noodles until you plan to eat the Salisbury Steak.
We use Glad Ware to freeze the patties in and put the sauce in a ziploc bag inside the same Glad Ware.
To reheat: Either defrost overnight and then reheat in the microwave or a skillet or from frozen, reheat in a covered skillet. Simmer patties in sauce until warm.
TIP: If you like a saucy salisbury steak, double the sauce.