Do you think if you were white he would not have done the exact same thing? Just curious... I can envision a stupid, seriously unfunny guy doing the exact same thing, without trying to be subtly or overtly racist. Combined with the situation, it might become racist, though, even if not intentionally so. But it could have been intentional, subtle racism, too. In either case, I'm glad you didn't spit in his food. I think that should be a serious criminal offense. It's disgusting and unhealthy, and would do nothing to solve the issue of racism in this case.
Hard to say if he woulda done the same thing if I was white, but cmon now, any sane person would realize how that joke would come off if it was directed at a Chinese guy. It's like making a legitimate joke about fried chicken but in the presence of a black guy, it's just not gonna come off in a good way. Yeah spitting in people's food is disgusting, that's why I've only spit in a customer's food once, and that was like 15 years ago when I worked at a breakfast place.