– grass-fed ground beef (85% to 90% lean) – egg – ketchup – yellow mustard – water
In a medium mixing bowl, combine the ground beef, egg, ketchup, and mustard. Use your hands to stir together and then form four patties.
Place the patties on the tray of an air-fryer. Pour the water into the bottom of the basket.
Cook the burgers at 360°Funtil the tops of the burgers have browned and the burgers are cooked to a medium doneness.