To remove old food from aluminum foil facing after cooking, start by letting the foil cool down to avoid burns. Then, use a plastic scraper or the edge of a credit card to gently scrape off the food particles. For stubborn residue, you can soak the foil in warm, soapy water for a few minutes before scrubbing with a soft sponge or cloth. Avoid using metal scrubbers as they can scratch the foil. After cleaning, rinse thoroughly and dry before storing or reusing.