Admittedly, I used to do this all the time when meeting Asian girls....
Guys- If you subscribe to the concept of not doing/saying things that every other dude says, then take caution asking Asian girls what their nationality is. I know, it's good information to know, but you have to realize that every.. I mean EVERY AFC asks them this... often as their opener. It's lame, guys. Just as you shouldn't make "tall" comments to a tall girl, etc, don't ask an Asian girl what her nationality is.
(Edit to add)
It think it's OK to ask this in comfort or later... Still, I think you should be tactful about it. After all, and especially this early in the game, why do you give a shit what her nationality is? It's just something for lame AFC's to ask because they want to talk to the HB and don't have anything better to ask/talk about.