Dan Barash, director of research and development for Moe's Southwest Grill, worked his way on a recent morning through a replica of Moe's kitchen assembled in an office building on the outskirts of Atlanta. Barash spent the first part of his career as a chef at fine-dining eateries, such as the Capital Grille and Roy's, where entrees alone could hit $40. But on this day, Barash and a small crew were busy whipping up more than a dozen burritos, quesadillas and rice bowls designed to sell for $7 or less.