Honestly fresh carrots are so good if they're from your yard or you can get them from a local source. Store-bought carrots from several states away just don't taste the same.

Depending on your definition of prep, I would also recommend apple, walnut, coconut yogurt medley with lots of cinnamon. You have to prepare the yogurt ahead of time though (no heating involved).

If I'm just snacking for no reason, I also like to eat nori...not many calories there though.