Examples of racist incidents that left black and Asian staff uncomfortable include:

Being regularly mistaken for other colleagues with similar skin tone

Negative comments about fasting during Ramadan

Treating black skin, hair and appearance as matters of fascination and touching hair without consent

Rude comments about minority celebrities, politicians or events

Some of those could be racist...maybe...it entirely depends on the context of the situation. The top one yeah, could be absolutely racist. The rest, it depends on context. If people think the idea of fasting is stupid, but respect your choice to do so, is that racist? Are the comments about a minority celeb because they're a minority, or because they've done something horrible, like were people critical of Kanye West having his daughter undergo a virginity test because its weird, or because he's black, context matters.

The hair one..people, stop touching others hair. Do i really have to say this? Don't touch people's hair, don't ask to touch it, just don't. If you ever have the thought "I want to touch their hair, I'm going to ask if I can", slap yourself in the face, and then maybe, just maybe we can pavlov's dogs this behaviour out of you.