Alan Caldwell, owner and pitmaster at Fargo’s Pit BBQ in Bryan, has been very protective of the cooking secrets that help make his joint one of the top two or three in Texas. In the past, he has refused to tell the Posse and BBQ Snob Daniel Vaughn the kind of pit he uses or the kind of wood he burns. “You still refusing to show anyone your pit?” he was asked during our weekend barbecue tour that covered 700 miles and took us to the Texas Gulf Coast. “That’s my secret,” he said. “Let’s talk about something else.” After…