Sprinkle salt and pepper on both sides of cube steaks. Combine flour and garlic powder in a shallow bowl.
Heat oil in a 10″ skillet over medium-high heat. (Use an iron skillet if you have one.) Dredge steaks in flour mixture, making sure they are evenly covered, and shake off excess flour.
Cook steaks in hot oil until brown, 3-4 minutes per side. It may be a tight fit for the meat, but it will shrink as it cooks.
Place sliced onions and mushrooms evenly over steaks, then add beef broth to just cover the contents. (You can add a little water if you don’t have quite enough broth).
Add worcestershire sauce, and bring to a boil, then reduce heat to medium-low and simmer at least two hours. (Loosely cover pan during simmering.) Meat will be very tender, and gravy will be thin. Serve over rice.