Key limes or Mexican limes used in Key lime pie are very different from the usual “Persian” limes that we usually see. Key limes are smaller, more acidic, and the flesh is yellow. Once dried into black lime, they are a useful ingredient in Middle Eastern cookery. The strange thing about both Key limes and Persian limes is that they are ripe when the flesh is yellow, not green.
As it’s sometimes hard to get hold of Key limes, I use normal limes. But if you can get hold of Bengali lim