Anyone who would say that Thailand is not a 'yogurt culture' culture has not been to a 7-11 lately and looked at how much refrigerated shelf space is given to yogurt products ... and 7-11 knows how much revenue is generated by every linear centimeter.

I went to Jet Sip-et today and bought som tum and whiskey so I guess that makes me a genius

That's too easy ... I'll leave it for someone else.

The problem with just using a spoonful of yogurt as a starter is whether the yogurt has been treated to kill the bacteria. Most commercial yogurts have!

I think that this is an health food industry urban myth, although it might have been true many years ago. All know for sure is that my very knowledgeable Thai doctor told me that most brands here contain live cultures and other people have verified this.

Remarkably enough, Ulysses is correct. Most commercial yogurts do have active cultures. The only exceptions I know of are those yogurts that are sold with the fruit or other flavoring evenly distributed throughout the yogurt. Yogurts with fruit or other stuff on the bottom are, as far as I know, active. There may be other exceptions to this, but if there are, they are not a significant percentage of the market.