Heat cooking oil in a large skillet over medium heat.

In a mixing bowl, combine the minced ground beef, onion, ketchup, Worcestershire, egg, seasonings and bread crumbs together then form into patties (about the same size for even cooking).

Place the Salisbury steak patties into the skillet and cook on each side until browned. About 4 minutes per side. Transfer to a plate and set aside.

Add the butter, mushrooms and diced onion to the skillet and sauté
for about 3 minutes or until the mushrooms have browned and softened.

Next, add the flour and stir to combine. Allow to cook for about 2 minutes.

Next, add the beef stock and stir to combine. Be sure to scrape up the brown bits from cooking the beef patties for added flavor.

Season with salt and black pepper; reduce the heat to medium-low and bring to a simmer.

Return the Salisbury steak patties to the skillet and simmer for 20 minutes.

Serve the Salisbury steaks topped with homemade mushroom gravy along with a couple of your favorite sides.