After a few minutes they're moved off the heat and continue to cook to their desired level of doneness over indirect heat. In other cases even brief periods of direct cooking are unnecessary because the food will be sufficiently browned using the indirect method. Preheating helps to burn off any food residue from previous meals that has adhered to the cooking grate or the radiant material, and also it brings the grill up to a temperature that will cook food properly, without sticking. Cleanup will be a snap if you remember to coat the grill rack with nonstick vegetable spray before beginning to cook. Just don't spray the grill over a live fire or you could start a flare-up.
Many variables can affect the cooking time of gas-grilled foods.
To avoid losing too much heat during cooking resist the urge to frequently open and close the grill lid, every time you do you're loosing heat and adding to the cooking time. Aside from several sturdy, heatproof, long handled tongs, basting brushes, spatulas, and forks be sure to keep a trusty instant-read thermometer near your grilling bag of tricks. For the best results allow food to reach room temperature before grilling. Generally speaking, this means removing it from the refrigerator approximately ten to fifteen minutes prior to grilling. Preheat with the burners on high, and with the lid down.