Is the problem that your wife is his sole source for access to asian women, and she's running out of women? ;-)
Instead of just asking out random women, he should just get involved in whatever genuinely interests him...but do it in a place or with an organization that has a high participation rate for asian women.
For example, does he go to church? I'd suggest he look for churches that emphasize multi-culturalism, like NewSong in Irvine or Mosaic in Los Angeles. Tons of single asian women there.
Join professional organizations that cater to asians/minorities. www.apex.org
Check out his school's alumni associations and get involved in the ones that cater to asians/minorities. For example, I see that UCI has a Chinese Alumni Association.
If he hasn't gone to grad school and was thinking about it, tell him to go to grad school at UCI or UCLA.
Just tell him not to act too desperate once he finds a group that he clicks with--all women can smell desperation, and it isn't attractive. No one will take him seriously as a potential mate if he gives off the impression that all asian women are fungible goods and that it doesn't matter which one he gets as long as he gets one.
I know plenty of "normal" asian women who married white guys. They usually met through mutual friends, at school, at work, or through their involvement in some shared interest. If he wants a "normal" asian women, I don't know if picking her up cold in a restaurant is the best strategy. Without any social context as to who he is, a "normal" asian woman would probably write him off immediately as some weird white guy with an asian fetish.