Pour 1 cup of white vinegar into the cookware after the pan has cooled.
Add water to the cookware until the burnt area is covered.
Put the cookware on high heat until the white vinegar solution boils. Let it boil for 5 minutes.
Pour the white vinegar solution down the drain. Let the cookware cool enough that it will not burn you. Scrub the pan carefully with superfine steel wool.
Repeat the process until the burnt cooking oil stain is gone. Rinse the cookware with water, and dry it completely.