For an extra layer of flavor, consider adding a dash of Worcestershire sauce to the ground beef mixture. If you don't have sherry vinegar, you can substitute it with white wine vinegar or apple cider vinegar. Feel free to experiment with different types of cheese, such as Gruyere or pepper jack, for a unique twist. Make sure not to overcook the patties or they will become dry. Use a meat thermometer to ensure they reach an internal temperature of 160°F (71°C).