Mix together the soy sauce, garlic powder and onion powder in a large bowl. Add the ground beef, egg, breadcrumbs, salt, pepper, and onion powder. Do not overmix. Mix until well combined. Shape into four equal patties.
Heat 2 tablespoons butter in a large skillet on medium heat. Cook the ground beef patties for 4 minutes each side, or until they are browned. (They will brown further in the sauce later). Place the skillet on a plate.
Reduce the heat to medium. Add the butter. Cook the mushrooms and onions sliced for 5-6 minutes, or until they are softened and golden.
Cook the garlic for one more minute.
Stir the flour into the mushrooms, onions, and garlic. Continue cooking for 1 minute.
Stir in the Worcestershire sauce, beef broth, and salt to taste. Cook for 5-6 minutes, stirring often.
Place the hamburger steaks in the skillet, along with any juices from the plate. Cover them with the gravy.
Cover the pan with a lid, reduce heat to a simmer, and continue cooking for 10 minutes.
Cook the sauce for another 10 to 15 mins.
Garnish with chopped parsley