Left: The fire and coal pile inside the cob oven BEFORE we started cooking. Right: The interior oven now ready to cook. I used a metal hoe to scrape the coals to the back and outside walls, clearing off the cooking surface. To clean off the residual ash on the cooking surface, you can either use a clean, damp mop or (what I prefer) a very quick sweep of the surface with a thick oven mitt. 