Blend golden mushroom soup, prepared mustard, and Worcestershire sauce in a bowl.

In a separate bowl, combine ground beef with 3/4 cup of the soup mixture.

Add beaten egg, fine dry bread crumbs, chopped onion, and salt to the beef mixture.

Shape the mixture into 6 patties.

Brown the patties in a skillet over medium-high heat.

Remove the patties from the skillet and drain off any excess fat.

Return the patties to the skillet.

Stir in the remaining soup mixture, water, and parsley (if using).

Cover the skillet and cook over low heat for about 20 minutes, stirring gently occasionally, until the patties are cooked through and the gravy has thickened.