A special IATA meeting was held in London to define a sandwich, and hear violations. The airline industry body declared that sandwiches had to be “cold… simple… unadorned… inexpensive” and had to “consist of a substantial and visible chunk of bread.” Moreover they could not contain anything “normally regarded as expensive or luxurious, such as smoked salmon, oysters, caviar, lobster, game, asparagus, pate de foie gras” nor could they feature “overgenerous or lavish helpings which affect the money value of the unit.”
Probably cream with berries or fruits. They're good when done right