Lox was sort of “invented” in Brooklyn, New York. Pacific salmon would be shipped east packed in salt. It was allowed to stay in the salt for 3 months, then it was soaked in water to leach most of the salt out. Now the cure is done more deliberately in a brine, often flavoured with brown sugar, for anywhere from 3 to 6 months.
It is eaten as sold; no further cooking is done or needed.
Lox is silky smooth, not flaky, and has a salty taste.
Lox is considered a very Jewish food, though it’s actually an American Jewish food — it is not very common among Jews in other parts of the world. In fact, it’s really only common in Eastern North America, perhaps from New York up to Montreal.
Language Notes
The word “Lox” comes either from the Scandinavian or the German word for salmon, lax or Lachs (both by the way closely related to the old Anglo-Saxon word for salmon, leax). In Yiddish, salmon is “laks”. Lox is also called “Belly Lox”.