Eli5: What’s so special about sous vide cooking that can’t be done via other cooking methods?
In: 3670
There are two main reasons why sous vide is so good. The first is just the mechanics of cooking; a steak for example is going to heat from the outside in as heat is applied. The proteins that make up the meat are going to undergo chemical change from this heat and there is a point where they will become overcooked and shrivel up, becoming tough and unappetizing (if you like your steak “well done” this is what you are getting, you heathen). On the other hand you do actually have to warm up the interior of the steak a bit to get it cooked at all instead of being raw. Unfortunately the heat applied from outside is enough to reach that excess cooking temperature so cooking a steak is a balance between applying heat slowly enough to allow it to work its way into the interior and cook the center sufficiently before the outside of the steak is ruined.
Sous vide sidesteps this issue by heating a water bath to a precise temperature and holding it there for a long period of time. The proteins of the steak can be heated to the point where they are cooked to an appetizing level, but not heated too much to become tough and excessively chewy. This kind of fine control on the level of a few degrees isn’t something you could do with other cooking methods, and certainly not over the period of time it takes! The speed of heat transfer increases the larger the difference between the two temperatures, so applying high heat to a cool object will transfer heat much more quickly than low heat to the same object. Cooking a steak sous vide then can take 1-4 hours since the heat that is applied is relatively low compared to an oven or skillet.
But this leads into the other major reason why sous vide is so good. The margin of error for time is increased dramatically. If you are cooking a steak on a skillet for example it will take 2-3 minutes per side on high heat for medium rare. What happens if you cook it for 3 extra minutes? You get boot leather. With sous vide though your steak might be done in 2.5 hours, but you are free to take it out an hour after it is done and it will be just fine! Obviously you need to do more planning ahead with sous vide since your steak won’t be ready in 10 minutes, but it provides a lot of scheduling flexibility for those of us who can benefit from that. Many restaurants can also benefit from this technique as steaks can be fully cooked and held on-hand for whenever people unexpectedly order them, increasing the speed of order fulfillment. For the home user you can season a steak, drop it into a plastic bag and a water bath, and monitor the cooking of your steak via smart phone app while you do something else.
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