Introduction: Sous Vide Cooker!
Wouldn't it be great if you could have a steak that is perfectly cooked all the way through? How a bout a piece of chuck steak that cuts with a fork and tastes like Filet Mignon? These things are possible with a Sous Vide cooker.
Here's how it works. Season your meat and seal it in a plastic bag, then submerge it in a water bath at the final serving temperature. Since it never gets hotter than serving temperature, it can't overcook. Unlike braising, where excessive heat causes collagen in the meat to squeeze out all of the juices, this lower temperature cooking method causes the collagen to transform into gelatin instead. You can leave a tough piece of meat in the bath for 24-72 hours and it still won't overcook, but it will become tender and the seasoning will permeate the entire piece of meat.
When you remove the meat from the bath, give it a quick sear in a frying pan to caramelize the outside and create a nice crust. This is the best way to cook meat, bar none, and once you try it you'll never go back.
Step 1: Tools & Materials Needed
- Drill and bits
- File or grinder
- Wire cutter
- Small socket
- Electric kettle, skillet or crock pot with a removable temperature control
- PID controller. This model has a built in 10 amp relay. If your donor kettle draws more than this, you'll need to add a higher current relay. There are other controllers that are sold with relays too.
- Heat resistant cloth
- Project box
Step 2: Theory of Operation
These skillet temperature controllers work by connecting a heat detector to the base of the skillet. Inside the case is an inclined plane that moves an electrical contact in relation to a piece bi-metal attached to the heat sensor. This bi-metal moves quite a lot with even a slight amount of heat applied. Still, the accuracy is all over the place. For cheaper units it can be a range of 50° (F).
By replacing the bi-metal temperature controller with a PID controller, we can bring that accuracy down to a range of less than 5°. A proportional-integral-derivative controller (PID controller) is a control loop feedback mechanism widely used in industrial control systems. Basically it's a super accurate thermostat and it's the key to making this project work. The one I chose for this project had 10 amp relay built in and only cost $17. I got the electric kettle at the thrift store for $4 making the whole project under $25.
Step 3: Gut the Bi-metal Controller
Do I need to say unplug the temperature controller from the wall?
Disassemble the temperature controller. There will likely be a screw hidden under the foil applique on the knob. Take it apart and cut the power wire from the mechanism inside. The neutral side of the power cord will go directly to one of the heating element power contacts. Leave this one attached and only cut the hot side attached to the adjustable contacts.
Set the cord and plastic case aside for now. We're going to work on the temperature sensor next.
Step 4: Gut the Temperature Probe
Most of these are made the same way. The bi-metal is spot welded on the side of the probe. The tip is welded too, but it's finished so you can't really tell. Drill out the spot weld in the side and grind off the tip just enough to free the innards.
Step 5: Install the Thermocouple
There is a thermocouple that comes with the PID controller. Enlarge the hole in the tip of the temperature probe just enough so it fits in snugly. Using a hammer and a small socket, swage the probe to lock the thermocouple in place. Swaging is forming metal. In this case we are shrinking the tip of the probe around the thermocouple locking it in place.
For some reason, they don't put heat resistant wire on the thermocouple. To protect the wire, make a tube of heat resistant cloth and slip it into the probe between the wire and the metal tube.
Step 6: Wire It Up!
You'll notice the omission of solder from this ible. It seemed the best way to attach the power was to open the original crimp connector and crimp the hot side back on the original connector for the heating element.
I've provided a crude schematic of the wiring. From the plug, the neutral side connects directly to the heating element. The hot side goes into the PID controller and out the provided relay contact. Removing the knob left a hole that I covered with a quarter to keep small fingers out.
Step 7: Test It Out!
Plug it in and test it. If the PID controller turns on and off, it's probably working properly. Cook a piece of meat in it. 56° (C) or 135° (F) is perfect. It takes about an hour to get a frozen steak up to temperature and if it's a tougher cut you'll want to leave it in overnight. Once I was confidant it was working right, I put the PID Controller into a plastic project box and now we use it almost every time we cook.
We buy cheaper cuts at the Costco and season and seal them before freezing them. I toss a couple in the sous vide on the way to work and it's cooked to perfection and tenderized when I return in the evening. Costco, Trader Joe's and even my local supermarket actually have seasoned meats in sealed bags that are perfect for the sous vide too.
For recipes and ideas, visit www.sousvidely.com for dozens of offerings by Instructibles own Scoochmaroo.