Just mix about two tablespoons vinegar per half cup water to cover burned areas (at least up an inch the side of the pan). Boil for 5 minutes then use a brush to remove all the food. If you have any tough spots, empty liquid and add some baking soda and continue scrubbing.
Here is another household tip. You can’t believe how easy it is to make your grill non-stick! You won’t believe this trick!