I usually make this for Once a Month Cooking, so I have made some adaptions. But it is excellent. My husband's favorite.

Salisbury Steak with Mushroom-Onion Gravy
Recipe By : Adapted from a Woman's Day recipe 9/1/96
Serving Size : 4

1 envelope onion soup mix -- (from a 2-ounce box)
2 cups water
1 1/2 pounds ground beef round
1/4 cup parsley, chopped -- lighly packed
1/4 cup all-purpose flour
1 1/2 tablespoons butter or margarine
1 large mild onion -- halved and sliced
2 4 oz mushrooms, canned
1 beef bouillon cube

1. Mix 2 tablespoons of the soup mix and 1/4 cup of water in a large bowl. Add beef and parsley and mix with hands until blended. shape into four oval patties, about 5 inches long and 2/3 inch thick.
2. Coat patties with 1 1/2 tablespoons of the flour. Melt butter in a large skillet over medium heat. Add patties and cook about 10 minutes, turning once, until crusty and no longer pink in the middle. Remove to a plate..
3. Add onion, mushrooms and 1/4 cup water to drippings in skillet. Stir with a wooden spoon to scrape up any brown bits on bottom. Reduce heat to medium-low, cover and cook, stirring occasionallly, until onions are soft, about 10 minutes. Stir in mushrooms.
4. Mix remaining soup mix, 1 1/2 cups water and 2 1/2 tablespoons flour in a 2-cup measure or in a bowl. Stir into mushroom mixture, add bouillon cube and bring to a boil. Cook, stirring often, until thickened, about 3 minutes. Pour some gravy into a 8 inch pan, then place patties on top. Add the remaining gravy over the top. Then cover and label. The day before serving, thaw in refrigerator overnight and reheat at 350F for 30 minutes.

NOTES : I usually serve with cream cheese potatoes and peas.