The outside portion where the majority of the heat would be dissapated. I've tried a light coating of oil before cooking to see if it would season while cooking. I live in south Alabama, and the grill stays outside and its usually dark outside when I'm cooking. I generally cook and let the coals die out overnight, which may be the source of my problem. I love the grill and will use it forever, just having a tough time keeping it black...
I'm new to the forum but an experienced CI user and have recently started collecting...