Place a few drops of dishwashing liquid into the cookware, and mix in 2 tablespoons of baking soda. Add hot water to the cookware, let it soak for a few minutes, then scrub the cookware with a stiff bristle brush in a circular motion.
Pour 1 quart of water into the cookware, and mix in 2 tablespoons of cream of tartar. Boil the solution for 10 minutes, dump the water, and then scrub the cookware again after it cools.
Place the cookware into the freezer for a few hours, then scrub the food off the surface. Food is easier to remove when it's frozen.
Pour water into the cookware until the stain is submerged, then add 1 teaspoon of white vinegar for every cup of water inside it. Boil the water for about 10 minutes, then empty the water and scrub the cookware after it cools.