Lewis was hooked, but knew he could do better. He hunkered down studying convection cooking, and both thermal and fluid dynamics. He needed to figure out ways to cook with indirect heat, creating consistent, even temperatures through convection -- as opposed to direct, radiant heat, which creates fluctuating heat and uneven cooking. This is common in the barbecue game. But most off-set smokers are vertical -- like the garbage cans, but bigger -- and they have rotating conveyors inside. You have to move around brisket to make sure it doesn’t singe in hot spots. Lewis figured out the exact thickness and material to insulate the walls to keep the heat in too. And because the long, round tanks and smooth edges on Lewis’ smokers are the perfect shape to keep heat and smoke circling consistently through, there’s no need to get up and move product around. Smoke stacks are rolled to a specific diameter. When I asked Lewis what that diameter was, he demurred. These specs are top secret.
When the pits are fired up, a grey plume swirls from the smokestack like a tornado. “The heat is seeking out a cooler spot,” Lewis says. “Because it wants to equalize itself.” When he had the design he wanted, he lit up the smoker for the first time the same day he put the smokestack on. “We weren’t cooking anything,” he says, “I just wanted to see what it could do.” Lewis had it on the driveway on the side of his house in Austin. He put a chair down 10ft away from it, opened a beer, and lit a cigarette. “There was a door open on the smoker,” Lewis tells me, “and the convection sucked my cigarette smoke into the smoker.”