To remove brown stains from stainless steel pans, mix 2 tablespoons of baking soda with 1 cup of water. Apply the paste to the stained areas and let it sit for 15 minutes. Scrub gently using a sponge or non-abrasive cloth, then rinse with warm water. Another method is to create a paste from equal parts vinegar and cream of tartar. Apply it to the stains, let it sit for 30 minutes, then scrub and rinse. For tough stains, try boiling 1 part white vinegar and 3 parts water in the pan for 10 minutes. Let it cool, scrub with a sponge, and rinse. Avoid using abrasive cleaners or steel wool, as they can scratch the stainless steel surface.