Let's say there was a machine that would allow you to cook anything to the exact perfect degree of doneness, every time, with no effort or labor. Would chefs use a thing like that? You're damn right they would — and they do it all the time, with the vacuum-simmering system called sous vide. This technique might be the biggest advance in cooking since the gas oven, and now sous vide machines are becoming available to home cooks for a few hundred dollars. (A vacuum sealer, sold separately, is another couple of hundred.) The humble-looking water baths are the Apple IIs of cookery. Expect to see more of them — a lot more.