In a large mixing bowl combine the ground beef, breadcrumbs, eggs, Worcestershire sauce, onion powder, garlic powder, salt, mustard powder, and black pepper. Mix well to combine and shape into 6-8 equal sized oval-shaped patties.
Heat a large skillet over medium-high heat. Add the oil and swirl to coat the entire surface of the skillet. Add the patties (you may not be able to cook all the patties at one time- work in batches as needed) and cook until browned and sides are crispy. Flip the patties and cook on the other side (approximately 1-2 minutes each side).
Remove from the skillet and set aside to a clean plate. Repeat with any additional patties as needed.
As soon as the Salisbury steak patties have finished browning, return the skillet to medium heat. Melt 1 tablespoon of butter and add the onions. Cook the onions, stirring frequently, until they are soft and golden.
Stir in the mushrooms and cook for an additional 4-5 minutes, stirring often. Add the garlic and cook for 1 minute more.
Stir in the remaining 2 tablespoons of butter and sprinkle the onions and mushrooms with the all-purpose flour. Stir continuously to remove any lumps.
Slowly stir in the broth, whisking continuously to remove any lumps that may have formed.
Add the Worcestershire sauce and season with salt and pepper, to taste.
Reduce heat to medium and simmer until the gravy starts to thicken (approximately 10 minutes). Stir often.
Tuck the Salisbury steak patties back into the gravy and cook until the patties are cooked to desired doneness (approximately 5-10 minutes), gently stirring the gravy around the patties every few minutes. Season with additional salt and pepper, to taste.
Serve patties topped mushroom sauce. Enjoy!
This recipe makes 8 Salisbury steak patties for a total of 8 generous servings. Should you decide to cut the recipe in half, you may cut the entire recipe in half or just the total amount of Salisbury steak (4 patties rather than 8) and keep the extra gravy (highly recommended).