Citrus bergamia, as it's known in botanical circles, first showed up 300 years ago in Southern Italy, the result of crossbreeding a sour orange with "something else, " variously identified as a citron, a lemon, a lime or a Palestine sweet lime.

WSJ: Bergamot Is No Lemon

The acid from the lime, lemon or orange juice changes the structure of the proteins in the fish much in the same way that heat does. (If you make it at home, you can observe the flesh turning from translucent to opaque.) Therein lay my answer.

NPR: Cool and Comforting Ceviche

You can omit the white chocolate without much harm and lime or orange can be swapped for the lemon zest.

NPR: How to Eat a Cupcake

The egg creams (soda water mixed with chocolate or vanilla syrup and milk) and cherry-lime rickeys (lime juice and maraschino cherries mixed with lemon-lime soda) are not to be missed here.

BBC: New York City��s classic diners survive