To cook over an open fire. First create coals . Build a prymid style campfire. Let the fire burn down. Shovel some of the coals to the side. Put a steel grate over the coals. Then put your cast iron skillet on the grate. Do not cook over an open fire but use coals to the side. As you are cooking the fish shift the skillet around the grate . Make sure the grate is even. Use a spatula to take the fish out of the skillet.