The formula for a really popular appetizer is something like “hand held + deep fried + cheese = moneymaker.” The burger-and-beer joint at the Cosmopolitan takes it one step further by combining a couple of different concepts: the egg roll and the Reuben sandwich, and executes it really well. Puffy egg roll wrappers are the perfect delivery vehicle for tender corned beef and sauerkraut. Things stay neat with a side of Russian dressing in which to dip the fusion appetizer. $12, in the Cosmopolitan, 698-7940, HolsteinsLV.com.