Put a couple of tablespoons of baking soda (more for serious episodes) and water in the pot or pan and heat to a boil. Let it soak until it cools and then clean with dish soap and a plastic scouring pad. You can simmer it longer if it needs a second try and /or add the dish soap to the baking soda solution. Or try a cup of vinegar instead also mixed with water and then boiled / simmered. Or try 1/2 cup of hydrogen peroxide and soak without heat. I like the baking soda method best.