To grill by the Indirect Method on a gas grill?

To grill by the Indirect Method on a gas grill, preheat the grill with all burners on High. Then adjust the burners on each side of the food to the temperature noted in the recipe and turn off the burner(s) directly below the food. For best results, place roasts, poultry, or large cuts of meat on a roasting rack set inside a disposable heavy-gauge foil pan. For longer cooking times, add water to the foil pan to keep drippings from burning.

Source: Weber