In a large bowl, combine ground beef, breadcrumbs, egg, Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Mix until just combined.
Divide the mixture into 4 equal portions and shape into oval patties, about ¾ inch thick.
Heat vegetable oil in a large skillet over medium-high heat.
Sear the patties for 3–4 minutes per side until browned. Remove and set aside.
In the same skillet, add the sliced onions and cook until softened and golden, about 5 minutes.
Sprinkle flour over the onions and stir for 1 minute to create a roux.
Slowly pour in beef broth and soy sauce, stirring constantly until the gravy thickens.
Return the patties to the skillet, spooning gravy over them.
Reduce heat to medium-low, cover, and simmer for 15 minutes until the patties are cooked through (internal temperature of 160°F).
Garnish with fresh parsley and serve hot over mashed potatoes or rice.
