With the grates removed, brush down the inside to clear out any loose particles that have collected in the bottom and around the sides. Scrape off any large peeling flakes of carbon and grease and if yours is a charcoal grill, empty the ash catcher. Don’t forget to clean the drip pan and grease cup in warm soapy water and line them with aluminum foil so they’ll be easier to clean next time.
To season the grill, rinse the grill grate with plain water, then dry it thoroughly. The next step is to apply a fat – either vegetable oil or shortening – to the grates, coating all of the cast iron with it. Place the grill grate over a cold grill, then slowly increase the temperature to about 400 degrees and keep it there for about 40 minutes. Finally, allow the grill grate to cool.
After about 30 minutes, turn the heat off and let the grill cool down. Wipe things down to remove any lingering residue and you should be good to go. The grill grates should have turned a bronze or dark brown color if they are metal or a darker brown/black color if they are cast iron. For cast iron grates, the oil will have penetrated the pores of the metal and created a smooth non-stick surface that will be perfect to cook on.
You also want a cooler, medium heat area of the grill to move the steaks to once they're seared and crispy on the outside. If you have enough burners and space on your grill, set them to a lower heat; if you don't have enough room, simply turn off the burner. If you are using a charcoal grill, one side should have a hot fire while the other a smaller, cooler flame.
If you're salting right before cooking: Again, let the steaks sit at room temperature for 30 minutes, sprinkle both sides (and the edges) generously with Kosher salt and freshly ground black pepper. Press the salt crystals and pepper granules into the meat. We like to brush our steaks with a little bit of clarified butter right before we grill them. You could use a refined high-heat oil or a mixture of oil and clarified butter.
Check the fuel lines for visible defects. If any fuel lines have unmistakable damage (like rips, holes, cracks), replace the parts immediately before your next use of the grill. Also be sure that any fuel lines have a smooth trail. You don’t want any of your fuel lines to be bent, because that will prevent the gas from flowing correctly. Check the exterior of the gas tank for any damage as well; things like dents, erosion, punctures, or any evident signs of damage. If you find areas that have obvious damage, you could potentially have a gas leak.