Food is passed around the table in a counterclockwise direction, or to the right. The reason for this convention is to provide some sense of order when serving or passing food. What's important is that when several dishes are being passed at the same time, they all go in the same direction. Otherwise, someone will end up with a dish coming from the right and another from the left at the same time. However, if someone only a few places away from you on your left asks for something to be passed, by all means just pass it to the left instead of sending it all the way around to the right.