01 -
In a medium mixing bowl, blend together ground beef, egg, panko breadcrumbs, A1 steak sauce, Worcestershire sauce, ketchup, steak seasoning, garlic powder, and onion powder until well combined.
02 -
Divide mixture into 4 equal portions and form each into a round patty approximately 3/4 to 1 inch thick.
03 -
Heat 1 tablespoon butter in a medium skillet over medium heat. Place patties in the skillet and cook for 5 minutes per side, or until fully cooked. Remove from skillet and tent with foil to keep warm.
04 -
Remove excess grease from the skillet, leaving about 1 tablespoon of drippings. Add 3 tablespoons butter, scraping browned bits from the pan, then add sliced onions. Cook, stirring occasionally, for 5 minutes or until onions are translucent.
05 -
Sprinkle in flour and stir continuously for about 2 minutes, allowing flour to brown lightly.
06 -
Gradually pour in the beef broth while stirring, ensuring all flour is dissolved. Cook for 3 to 4 minutes, stirring often, until gravy begins to thicken. Season with salt and black pepper to taste.
07 -
Add sliced mushrooms and the cooked patties back to the skillet. Reduce heat to low and simmer for 7 to 10 minutes, or until mushrooms are tender and gravy is thickened.
08 -
Serve the patties hot, topped with mushroom onion gravy. Accompany with mashed potatoes, rice, or vegetables as preferred.