I coat the outside with dish detergent and let it dry, then all the soot washes right off. Been lucky and haven't burned the inside yet!!! In my previous link to amazon, that is the same model, I bought it from a local retailer. It's not cast iron, just some form of thin metal so the soap works fine.
2010 Jay Flight 28BHS
2007 Yukon XL 2500 6.0L 4X4