For various reasons, I've been thinking a lot about trying out sous-vide cooking lately: I see it on cooking shows like Top Chef, food blogs that are much fancier than mine have been abuzz with the recently launched "Sous-vide supreme," an immersion circulator scaled down for home use that hit the market a couple months ago, and, more recently, I met a neighbor who has his own immersion circulator. I thought that my own forays into sous-vide cooking would have to wait until I felt like ponying up the $500 it would cost for the Sous-vide supreme, and then yesterday, I had one of those rare Eureka! moments when I was making a big batch of stock.
For some reason, I decided to monitor the temperature of the stock with my digital thermometer, and I noticed that when the burner we at it's lowest point, the equilibrium temperature was very stable. I realized that I could take advantage of this to set up my own water bath for some improvised sous-vide cooking. The difficulty with sous-vide cooking is that you want to set the water temperature to be at desired internal temperature for the meat that you are cooking, and for many meats, the temperature you want is pretty low. My stock pot was holding steady at around 180F, which is far too hot for most meat, fish, and poultry. The solution to this was to increase the surface area to volume ratio. This allows the heat to dissipate more rapidly, resulting in a lower equilibrium temperature.
I decided to use a heavy roasting pan for my make shift sous-vide. There are a few advantages to using a roasting pan. First, it has a lot of surface area, allowing you to achieve lower equilibrium temperatures. Second, it spans two burners, giving you an extra level of control over the heat. Third, it can fit a long cut, like a loin. And, finally, since this is a fairly heavy pan, it did a good job of maintaining a steady temperature.
When the pan was filled to about 3/4 of its capacity and both burners were on the lowest setting, the steady-state temperature was 133F. It was able to maintain this temperature for several hours. If I wanted to go lower, I could just use one burner, and if I wanted to go higher, I could just turn one or both of the burners up.
While it takes a bit of experimentation to figure out how to get to your desired temperatures, some might find it preferable to spending $500 on your own immersion bath. Eventually, I think it will be worth it to me to have the level of control that you get from an immersion bath that is expressly made for sous-vide cooking, but for now, this is a more than capable substitute. All it takes is a gas range, a large roasting pan, a digital thermometer that you can set to alert you if the temperature gets above a set point, and some plastic, vacuum sealed bags (You can get these at Target with a hand held vacuum sealer for a few bucks).