Yeah soap isn't really an option if you have a real barbeque with a well seasoned cast iron grill.

The whole "don't use soap on cast iron" thing is completely overblown, and comes from the old days of strong lye soap.

It's perfectly ok to use modern soap on cast iron. If that washes off the seasoning, it didn't deserve to be on there anyway.

I've read that's a common myth, that a little soapy water for a few minutes is going to do nothing to a polymerized fat coating that was seared into the pitted surface of cast iron under high heat, but even if you were concerned about it, a brief re-seasoning afterward would be more than enough to restore any stripping.

Low pH cleaners are fine. Higher pH such as dishwasher detergent will strip the seasoning.

I use warm soapy water to clean my cast iron pan and I haven't noticed the seasoning being affected.