"Flavor white" is a term to describe people of European descent who are often separated from other white people due to certain features, religion, or culture. This often describes certain Jewish people, certain Mediterranean people (Greek, Sicilian, etc.), and some white passing mixed people.
Sandy tans really well because she is Greek, so sometimes people think she may be hispanic. Really she is just flavor white.
Some people don't group ethnically Jewish people as white, even though they are. So, to make this distinction, they can be considered flavor white
My brother is mixed, but looks white. Some might consider him "white passing", but with his personality and knowledge of culture he is just flavor white.