I vote for the chef to apologize. But I personally think more needs to be done in his part.
My reasoning is that if they outright fire him, it'll only end up with the chef in question going somewhere else with his skills in the kitchen, and the process will continue, with the masses who follow and agree with him, backing him up and producing more racists.
The pragmatic move is to change the chef and have his followers be influenced in kind.
Of course, ignoring this is a stupid idea as well.