Rubens are classic sandwiches that are very common most places where I have lived. American style sandwich shops and restaurants usually have one on the menu.
Because of the name, I'd always assumed that they were originally a popular Jewish deli sandwich, but then one day I realized that despite the rye bread, the pastrami, and the name, a Ruben sandwich is not kosher because of the Swiss cheese.
So where do they come from? Are they served in authentic delis? Do they vary from one part of the US to another?