Lump only!. Screaming white hot keeps the ash to a minimum. Use something (like a big spatula) to wave off any ash just before setting the steaks. Be prepared for smoke and fire - that's a good sign. Don't move them until you are ready to flip! Don't drag them on the coals in any way. One or two steaks max on a load of coal, and aim for the hottest area you can find. Flip once only. A 2" ribeye is perfect rare with about 4 mins per side. Thinner cuts = less time.