
In a medium bowl, mix all of the steak ingredients except the oil together until well combined combined.
Shape the meat mixture evenly into 4 oval patties, about ¾-inch thick.
Heat the oil in a large skillet over medium-high heat. Add the patties and cook until well browned on each side, about 3 minutes per side. Remove from skillet and set aside.
Add the butter to the same skillet and melt over medium heat. Add the onion, mushrooms, and garlic. Cook, stirring frequently, until the onion is softened, about 5 minutes. Add the flour and stir constantly for 1 minute.
Gradually stir in the stock. Stir in the Worcestershire sauce, salt, and pepper. Bring to a boil, then reduce the heat to low.
Return the patties to the skillet, nestling them among the gravy. Cook until the patties are cooked through and the gravy has thickened, about 5 to 7 minutes. Serve garnished with chopped parsley.