Masso Osteria offers an off-the-menu burger

It’s not on the menu, so you’ll have to ask for it. It’s a half-pound of juicy ground beef, topped by a tangle of caramelized onions and a drizzle of truffle aioli. The Masso Burger is $18 during Social Hour, from 5 to 7 p.m. daily, at Masso Osteria at Red Rock Resort.