While your stainless steel pan is a hard and durable surface, burnt popcorn is a difficult substance to remove. Use a strong cleaning solution that gets off all that popcorn residue, but keep in mind that you want to avoid damage to the pan. Also, avoid use of chemical ingredients that could later be cooked into your food.
Things You'll Need
Nylon scrubbing pad
Pour 2 tbsp. baking soda into the pan along with 1 tbsp. dish soap and about 2 cups hot water.
Scrub off the residue with a nylon scrubbing pad.
Rinse out the pot and submerge the area with about 1 inch white vinegar. Let the vinegar sit in the pan for an hour.
Scrub the popcorn residue again with the nylon scrubbing pad. If any residue remains, pour more vinegar into the pan, and this time let it sit overnight. Scrub with the nylon pad the next morning.
Discard the vinegar and wash the pan with hot, soapy water to get rid of any remaining residue.