This recipe was one of 5 winners in the 2011 LA Times Burger contest. Cemita is the name of a sandwich popular in Puebla, Mexico. The name also refers to the bun which is an egg-rich bread topped with sesame seeds that is sort of a cross between challah and brioche. The papalo leaves are normally found in most Latin markets, but you can use a combination of cilantro leaves and watercress to mimic their flavor. The recipe was submitted by Harold Cohen of Hollywood, Florida.