Build a big fire.
You'll need a broad fire pit, at least three or four feet across. If you don't have access to one, make a ring of rocks big enough to hold embers; if you're on the beach, dig a shallow pit in the sand. An hour before cooking, build a roaring blaze on one side of the pit – not in the center. "Keep stoking it with logs right up to when you want to cook, so you don't run out of coals," says Mark Liberman, chef and owner of TBD in San Francisco.