You need to know someone in Asia (obviously). Ideally you've worked with them before, but if you got a contact in some other fashion, obviously you need to interview /talk to them, look at their code (I strongly suggest this), read their blogs etc, just the same as you would if you were hiring them for your startup in the USA/Europe.

If anyone is looking for good developers (no PHP folks, but say, RoR, Django, Java, C++ etc) in Bangalore, write to me. (No you don't have to pay me. I am a developer not a head hunter ).