Raw potatoes, or even better, other root vegetables sliced thin and crunchy.
Regular chips may technically be vegetarian, but this kind of chip is also vegetarian in spirit.
Dude: How's the party?
Bag: I'm doing okay, I brought my wheatgrass juice...do you have any snacks that are MORE vegetarian?
Dude: <picks up raw, unscrubbed potato with sprouted eyes and slices onto plate> Here, have some vegetarian chips.
Bag: Oh thank you!