Retrospective-Avatar: the Airbender Book 1, Chapter 13-The Blue Spirit
This was one damn good episode. The action was fan-tucking-fastic. It was much funnier than I remember it being, and not just the typical Avatar jokes but some drier humor as well. It also managed to give us a great hint to where Zuko's path would lead, while still having him be very in-character in the present. It's no wonder why it is considered by many to be one of the best in the season, and maybe in the show as a whole.