Cancel anytime. The Prosperity sandwich with roast beef, provel cheese, gravy and garlic butter at Ruma's Deli, on Thursday, April 14, 2016 in south St. Louis County. Photo by Huy Mach ...

Cancel anytime. The Prosperity sandwich with roast beef, provel cheese, gravy and garlic butter at Ruma's Deli, on Thursday, April 14, 2016 in south St. Louis County. Photo by Huy Mach ...

A deli roast beef sandwich is a wonderful thing: a succulent tower of paper-thin slivers of rare red meat, perched on sliced seeded rye, slathered with mustard. Properly made, it threatens to be ...