We’ve all heard of the virtues of cooking with cast iron. Rust on this cookware is not one of them. If you’ve shied away from cooking with pots and pans made of cast iron, try again! The inside of a raw potato peel will take the rust right off! This is because potatoes contain oxalic acid, which is the ingredient found in commercial rust cleaners. The peels work great on knives, baking pans, and any other cooking essentials.