Place ground beef in a large mixing bowl. Add breadcrumbs, egg, milk, chopped onion, garlic powder, salt, pepper, and Worcestershire sauce. Mix gently using your hands. Combine until just mixed. Do not overwork the meat or the patties will become tough.

Divide the mixture into four equal portions. Shape each portion into oval patties. Traditional Salisbury steaks are slightly longer than burger patties. Place them on a plate and let them rest for a few minutes before cooking.

Place a large skillet over medium heat. Add a small amount of oil or butter. Let the pan heat for about one minute. A hot pan helps the patties form a golden crust.

Place the patties in the hot skillet. Cook for about 4–5 minutes per side. The outside should become nicely browned. The inside does not need to be fully cooked yet. Remove the patties and place them on a plate.

In the same skillet, melt butter over medium heat. Add sliced onions. Cook slowly for about 5 minutes. Stir often. The onions should become soft and slightly golden.

Sprinkle flour over the onions. Stir well to coat them. Cook the flour for about one minute. This step removes the raw flour taste and helps thicken the gravy.

Slowly add beef broth while whisking. This prevents lumps from forming. Add Worcestershire sauce, salt, and pepper. Stir until the gravy begins to thicken and becomes smooth.

Place the browned patties back into the skillet. Spoon some gravy over the top. Reduce heat to low and cover the pan.

Let the patties simmer for about 10 minutes. This step finishes cooking the meat. It also allows the patties to soak up the delicious gravy flavor.

Remove the skillet from heat. Serve the Salisbury steak warm with extra gravy on top. It tastes wonderful with mashed potatoes or rice.