These are the shops where one sandwich is not just popular, it is the whole reason the front door keeps swinging open. Slyman’s Restaurant, ClevelandThere are sandwich days and then there is the day I first saw a Slyman’s corned beef hit the table and briefly forgot how conversation works. Izzy’s on Elm Street in downtown Cincinnati has built its reputation on corned beef and Reuben sandwiches, layering corned beef, Swiss, sauerkraut, and dressing on rye with the confidence of a place that has done the same thing, very well, for a long time. Kravitz Delicatessen, YoungstownSome delis talk about heritage; Kravitz lets the warm rye and corned beef do most of the speaking. Thin sliced corned beef, Swiss, sauerkraut, and dressing on grilled rye arrive with the kind of consistency that only shows up after countless practice rounds.