A retired Air Force brigadier general sought a new mission: to create the first certified mobile food-truck apprentice program in America. David Pogue talks with John Michel about Currency of Caring, which helps teach entrepreneurs (many of whom had been going through hard times) the food-truck business; and with Demetrius Gower, whose Big Meechie's Kitchen & Food Truck, in Granite City, Ill., has proven an award-winning success.