Scrape the grill grate surfaces, using a wire grill brush to remove as much of the caked-on food as possible. Scrape while the surface is still warm. If necessary, turn the grill back on or relight the charcoal to heat up the grates.
Mix 1 cup of water with 1/4 cup of apple cider vinegar in a spray bottle. Spritz the mixture over the warm grates. Use a clean paper towel to wipe the surface of the grates. Repeat three to four times until all food solids are gone.
Soak a sponge in water and liquid dish detergent. Wring out excess water and wipe the grate with the sponge to remove any grease. Run the grate under clean running water to remove the soap.
Dry the surface of the grill grates with a clean cloth.
Season the grill grates to make it harder for food to stick. Coat the grates with vegetable oil, using paper towels. Wipe the oil to the top and bottom of the grates. Wrap the grates with aluminum foil and place them back on the grill. Heat the grill with charcoal or gas for 10 minutes. Remove the grates from the heat and let them cool before removing the aluminum foil.