The last thing you want to do is stand over a grill all evening, taking everyone’s burger order one by one. Making one big batch of burgers and keeping them warm instead lets you kick back and enjoy the feast as well. If you’re planning on hot-holding your patties for an extended period, you’ll need to warm them regularly. Hamburgers held at the wrong temperature could create breeding grounds for bacteria.
Get a large pan out. A cake pan, hotel pan or even a cast-iron skillet will do the trick. Just make sure the vessel has at least a 2-inch lip around the sides, so juices don’t go dripping away.
Spray the entire inside of the pan with nonstick cooking spray. Place the pan on the top rack of your grill or on top of your stove -- if you’re broiling your burgers in the oven -- to keep it warm.
Put the small stockpot directly on a cooler part of your grill or on a low-heat burner. Pour a small amount of low-sodium beef stock or au jus into the pot. Allow it to simmer and heat up to at least 140 degrees Fahrenheit, while you’re cooking your hamburgers.
Cook your burgers thoroughly and test each one with a food thermometer. Ground meat needs to be cooked to a minimum internal temperature of 160 F, according to the U.S. Department of Agriculture's Food Safety and Inspection Service. Cooking your patties up to this temperature minimizes the risk of a foodborne illness breakout.
Place the burgers into the coated pan after you have checked their temperature. When your batch is complete, drizzle the warmed cooking liquid over the patties, leaving roughly half an inch of fluid at the bottom of the pan.
Cover the pan with aluminum foil, sealing it around the sides. The foil helps seal in the steamy heat from the hot broth, making a moist environment for your cooked patties. This way, they’ll be less likely to dry out. Leave the covered pan on the top shelf of your grill, on top of your stove or in your oven at a very low setting, so they stay warm.
Check the burgers' temperature with a food thermometer at least every two hours. They need to stay above 140 F. Consider rotating the patties as well, each time you check them, moving the ones in the back of the pan out to the front, as an example. This helps keep the temperature consistent throughout the pan.