The cut: Both come from the brisket, a long cut of fat and muscle stretching from a cow's foreleg to its underbelly. Closer to the leg, the meat is tougher, but at the other end, the "navel," it's fattier and juicier. Traditional New York pastrami usually takes the navel cut. Montreal delis often use the midpoint between the extremes of fat and muscle.
The process: Pastrami is dry-cured, meaning the meat is lathered with sugar and salt until absorbed, then seasoned with spices and smoked. Montreal smoked meat is also dry-cured, but then soaked (like corned beef) to desalinate it before seasoning and smoking. Montreal smoked meat smokes a bit longer than pastrami, capturing more of the flavouring.
The spices: Professional pastrami and smoked meat dealers will not reveal their recipes, but most of the added flavour comes from black pepper and burnt sugar.
Serving and slicing: Purists of both the pastrami and smoked meat schools insist that the meat must be steamed before slicing, and that it always be served warm and soft. The slicing should be done by hand, not by machine.
Where to get it: The best smoked meat on rye come with fries and pickles at Schwartz's Hebrew Delicatessen in Montreal. Schwartz's meat is so well smoked that it can last days without refrigeration. Of course, fresh is better. In New York, Katz's Deli on the Lower East Side is the oldest still-operating delicatessen in the city and the best place for a pastrami sandwich. It's pricey, but affords patrons an excellent sandwich and a seat from which to watch an eclectic cross-section of New Yorkers come together out of love for their sandwiches.
The myth: Pastrami, strictly speaking, is not a kind of meat. It's a process of preserving meat through curing and smoking. One can have turkey pastrami, pork pastrami, etc.