I tip less at buffets, but since I usually overtip in the first place, it's still in the ~15% range.
If it's a sit-down restaurant with a menu, I'll tip the usual (for me) 20% or so, since regardless of their races, they live here and pay the same for gas as I do.
How "Chinese" is a restaurant is when the ingredients are locally grown, the recipes originated in California (orange chicken is NOT chinese food), the server is Caucasian, the hostess Vietnamese, and the cook Mexican?
Oh well, it tastes good, and ya gotta have a job. Bottoms up!