Sous-vide (/suːˈviːd/; French for “under vacuum”) is a method of cooking in which food is sealed in airtight plastic bags then placed in a water bath or in a temperature-controlled steam environment for longer than normal cooking times (usually 1 to 6 hours, up to 48 or more in some select cases) at an accurately regulated temperature much lower than normally used for cooking, typically around 55 to 60 °C (131 to 140 °F) for meat and higher for vegetables. The intent is to cook the item evenly, ensuring that the inside is properly cooked without overcooking the outside, and retain moisture. –Wikipedia
True confession: I am a closet sous vider. I come from the last of the old guard that rejected sous vide in favor of more classical techniques. I was first exposed to sous viding when I did a stage for Joel Robuchon in Paris in 1996. He had a pork belly dish I vividly remember, the ultimate Petit salé aux lentilles, a melt in your mouth dish of cured pork belly served over creamy lentils. Petit salé is far too bourgeois for most diners of a three star Michelin restaurant and I am convinced the dish was not actually on the menu but there only for gastronomic regulars in the know. Each morning at Robuchon a plastic tub was filled with warm water and a strange device attached. The machine gently hummed while vacuum-packed bags of cured pork belly were lowered in. All throughout prep and service, the machine circulated water heated to a precise temperature around the packets. It felt like Christmas whenever someone ordered it. Time stopped. Everyone’s attention was fixated on the opening of that one single package and I always wondered who was on the other side of the swinging kitchen doors eating it. Since then, every “modern” kitchen I have worked in had at least one such circulator.
Finally, companies like Anova are making this extraordinary technology affordable and within reach for home cooks to use.