I had soaked it for an hour with a dawn solution and tried a toothbrush, a credit card, Mr Clean sponge, anything I thought that might work ... crud that could absorb water came off but the burnt on crap stayed. I tried brake clean, gasoline, PB Blaster, carb cleaner on the remaining residue with no luck. I thought for sure Brake Clean would cut the burnt on cooking oil glaze. So I tried baking soda and enough water to form a thick paste and that worked well with a little work and it did no damage. Adding white vinegar will make it fizz, I'll try it next time to see if it helps.