Combine the broth, lemon juice, soy sauce, garlic powder, and black pepper in a zip-top bag or plastic container. Add the steaks and turn to coat completely in the marinade. Seal the bag or cover the container and refrigerate for 1 hour, turning the steaks as needed. Preheat the grill or broiler. Remove the steaks from the marinade. Place on the grill or on a broiler pan and place under the broiler. Cook for 15 minutes for medium, turning as needed (add less or more time depending on desired doneness). Brush with the marinade every 5 minutes.