Grill-roasting involves cooking over indirect heat at a fairly constant temperature, mimicking the environment of an oven. It requires longer cooking times than regular grilling simply because the pieces of food are larger.
Because of that longer time, this technique calls for heat that is more moderate. The grill is typically set up with a half-grill fire for indirect cooking—that is, part of the grill is left free of coals, or some of the gas burners are turned off, to create two temperature zones.
As a result, large pieces of meat can be cooked through without danger of scorching the exteriors or drying out the interiors.