Quick Steam Method: Carefully place the slice of cheese onto the Burger. Use a restaurant condiment bottle to squirt water onto the grill around the Burger, then cover immediately with a pot lid or aluminum tray. Keep covered for 15-60 seconds (some cheeses take longer to melt than others). Remove cover to reveal beautifully melted cheese atop your Burger!
Remember: Adding water to a hot and or greasy surface can be dangerous. Be sure to take recommended safety precautions before attempting.