Mix beef, breadcrumbs, egg, milk, and seasonings.
Form into oval patties for Salisbury Steak And Gravy Recipe.
Heat oil in a skillet over medium heat.
Cook patties until browned on both sides.
Remove patties from skillet, set them aside.
Add butter to the same skillet carefully.
Cook onions and mushrooms until softened and browned.
Add flour, stir to create a smooth paste.
Slowly pour in beef broth, whisk until smooth.
Add Worcestershire sauce and simmer for 5 minutes.
Return patties to skillet, cover, and simmer 15 minutes.
Garnish with parsley before serving warm and fresh.