Mustard stains on an outdoor table can be stubborn, but with the right techniques, they can be removed easily. Start by scraping off any excess mustard with a dull knife or spoon. Mix a solution of warm water and dish soap, then gently scrub the stain with a soft brush or sponge. For tougher stains, create a paste using baking soda and water, apply it to the stain, and let it sit for 10-15 minutes before scrubbing. Rinse thoroughly with clean water. If the stain persists, try using white vinegar or a commercial outdoor cleaner. Always test any cleaning solution on a small, hidden area first to avoid damage to the table's finish. Regular maintenance and quick action can prevent stains from setting in.