Bánh mì (pronounced 'bun mee') is a popular Vietnamese variety of sandwiches that share the same core ingredient - a baguette. The baguette was brought over to Vietnam during the colonial period, and nowadays it is one of the few happy legacies from the time.
The crusty bread, condiments, and meats are all a legacy of French and Chinese colonialism, while cilantro, chili, and pickles reflect the Vietnamese taste for fresh vegetables and bright flavors. In the beginning, most banh mi sandwiches consisted of bread, meat, and seasonings, with no added vegetables.
The meat on the inside can be chicken, pork, beef, seafood, cold cuts, or pâtés, sausages, and terrines, but it is extremely important not to overstuff the sandwich. Most of the fillings and condiments are things that foreigners are unfamiliar with, and that just may be the secret to its popularity.