I've worked for a Thai restaurant before, and, in the restaurant at least, we always carve out a new one whenever its ordered. To explain Leland's answer below, we often pre-carve it when things arent so busy, then store it for later. If its a slow day or off-peak hours we often carve a new one. Of course we use a new one. read more
No one answer goes for all thai restaurants. My friend used to work at one back when we were in our early 20s and I remember her mentioning that the restaurant were reusing their pineapple bowls. Just because the one where she used to work at were doing that, does not mean other ones would. read more