A real easy way to clean your oven is to fill an oven-safe tray (like a baking pan or you can do this by placing oven-safe cups on a cookie sheet) with water and the juice from one lemon and both halves of the lemon on the middle rack. Heat the oven to 350° until the water boils. After a half an hour, remove the tray. The steam will have loosen all the grime so it will easily wipe off. The lemon scent fills your kitchen with a citrus aroma.