Dinner guests at Gwen, the Los Angeles restaurant and butchery helmed by celebrity TV chef Curtis Stone—who you may know from “The Celebrity Apprentice 3” and “Top Chef Masters”—may not see what goes on behind the scenes. To run a well-oiled machine at a fine-dining establishment like this requires the help of a good back-of-the-house manager like Darrell Stevenson, who was given a second chance at a career after others turned him away because of his rocky past.