All my pots and pans are stainless steel. I ditched all the non-stick Teflon pans years ago because of PFOA - perfluorooctanoic acid - a solvent used to make Teflon coated pans that are toxic to our health. I'll admit; it took months of getting used to stainless steel pans because, as you can imagine, everything sticks to the pan if I'm not careful.
But time to time, I get distracted and things DO stick on the bottom. And what's worse, the stain gets baked into the pan. And no matter how much I scrub, it does not come off....unless I use Brillo pads, which I hate to use because I don't like the soap that comes with Brillo pads. I even tried using copper scouring pads but it didn't work either. It just scratched the pan. Boo Hoo!
So, I decided to try the Non-Toxic Silver Polishing method, except, I replaced the Salt with Vinegar. The stain was worse than this when I started but I stopped the process so that I can take the photos for you to see.
Size and amount will vary depending on the size of your pans and the stains
Pour the vinegar and place the aluminum foil piece in the pan. Add baking soda. Swirl the pan around so that baking soda gets evenly distributed. While the solution is bubbling, gently rub the stain with the aluminum foil without scratching the pan's surface/finish. Rinse with water and dry thoroughly with dish towel. Voila! The scratches were already there as I was using the copper pads earlier. ;( I wish I thought of using this solution before I did that.