Bagels have been a part of Jewish cuisine for over 400 years. They have been made in the traditional way in countries all over the world, with only tiny variations influenced by the availability of ingredients. There are many places in the world that love the bagel as much as New York City.
The bagel is a donut-shaped bread roll, created from either water or egg-based flour. It's given its distinctive texture because it is boiled prior to baking. This process lends a unique chewy structure to the interior, and a thin, crispy outer shell. The bagels are often dipped in poppy or sesame seeds to add a further textural dimension to the crust.
Smoked and cured fish is a large part of traditional Jewish cuisine, given the restrictions of Kashrut dietary laws on the combination of certain meats with other ingredients. Lox is a dry-cured and lightly smoked salmon fillet, usually sliced very thinly and piled into tumbling folds. Lox is preferably more sweet than salty, and possesses a specific soft, smooth texture. Grainy or rubbery lox is not desirable, as it suggests the fish was frozen at some point. The sharp ice crystals that form in the flesh damage it as it thaws, altering the silky texture of the fish.
The traditional companion to Lox when served on a bagel is whipped cream cheese, often referred to as "shmear" in the Yiddish dialect. The word is similar to "spread" in English, as in, "cheese spread." It's both a noun for the dish, and a verb describing the method in which it is served. The cheese is sometimes mixed with additional flavors and seasonings, such as chives, paprika, lemon juice or red onions. As an additional time-saver, some delis, such as Atlanta's "NYC Deli & Coffee Company," finely chop the lox and mix it into the cream cheese, creating a blend of the two textures.
As with most popular traditional foods, there are purists who insist on the recipe remaining the same. However, there will always be people who want to try new things and create new flavors to experience. Some popular variations with bagels include adding herbs and seeds that complement the flavors of the lox; caraway seeds and dill are popular. Lox is largely left unaltered, as it is the clean, pure flavor that is the attraction.