In his cookbook called Mantra, which was released last month, Graffiti chef-owner Jehangir Mehta includes a recipe for a cocktail he calls “Barley Legal,” a cheeky mix of ultra-healthy barley water and Johnny Walker. "This drink is dedicated to all the young celebrities out there," the chef writes, introducing the recipe. And it’s probably a sincere note of acknowledgment, coming at the tail end of book filled with new and understated ideas about food. The......