Commercial Sous-Vide equipement is $450 for the low end. You can buy the equipement in this instructable for less than $50, and probably less if you have any of the pieces laying around.
Bonus Extra Instructables:
For less than $70 you can also build your own "PID" controller from an arduino with this instructable. An aquarium heater works well in a cooler to keep a constant temperature. Here is how to rig it to be always on. With those two projects you can have a "set and forgot" system that is accurate to 1 degree F.
This instructable is unique in the use of the hacked aquarium thermometer to heat the water when it starts to cool. It allows much more precise control than a tea pot heating method. If you don't want to hack a heater, I describe how to heat water on the stove. It's just more labor intensive. This method is still under manual control, but you just plug and unplug the heater. If you add the PID controller, it's all automatic.
Sous-Vide means "under vacuum". As a cooking method, it's a key to perfectly cooked meats that don't need babysitting or split second timing. It's even possible cook eggs and custards to perfection. This instructable will show you how you can experiment with this technique using equipment that is much cheaper. if you already have a water tight beer cooler and a vaccuum sealer of some kind, you might even already have everything you need. Douglas Baldwin's web page has a lot of information and recipes once you have the basics sorted out. Also check out EWilhelm's Sousvide instructable, which is partially what got us started. Eric uses a commercial temperature controller which allows more hands-off cooking, but increases the cost about double what our Aruino based solution did. If you want to try this cooking method out on the cheap, read through here and you can probably do your first meal with what you have laying around. Beware, you may get hooked on perfect steak and end up spending your weekends soldering up controllers for friends and family.
Step 1: Equipment
A watertight cooler of some kind.
Heavy duty zip lock bags or vacuum sealer bags.
A way to heat water.
A thermometer that can read water temperature.
Some kind of meat to cook. Steaks are recommended.
An electronic temperature probe with alarm. About $25
A food sealer. $10 for a hand pump or $300+ for a heavy duty sealer.
An aquarium heater that has been hacked to be always on. $25
An aquarium bubbler with enough airline to reach the bottom of the cooler. $10
A PID controller or other automatic way to keep the water temp constant. Like this instructable of mine for instance.
(optional) Hacking an aquarium heater.
You can just heat water on the stove and manage the water bath that way. However, having some kind of immersion heater makes things easier.
See my instructable on hacking a heater.
Warnings: Use your head. Don't plug the heater in unless it's mostly under water. Never thermal shock the heater or it will crack. Only use with a GFCI outlet. If something goes wrong, unplug it before you do anything else. Keep an ABC fire extinguisher handy.
Step 2: Prep the Water Bath
Fill your cooler enough that all your meat will be under water when you add it. I like to add quite a bit of water since it stabilizes the temperature.
Get your heater, bubbler and probe set up. I have floated a thermometer in the hole of a wooden spoon before I got the elecronic probe. The heater heats the water. The probe lets you know when the water is at the right temperature. The bubbler agitates the water to prevent cold or hot spots. If you don't have a bubbler, you can stir the water or hope that there is enough convection to keep the water at the right temperature. Because the whole unit is sealed inside of the cooler, the temperature will be within a few degrees all around fairly quickly even without the bubbler.
Using your hacked aquarium heater and/or a tea kettle on the stove, get the water to the temperature you wish your meat to end at (for beef this is likely between 135 and 145F). For these steaks I set the temperature at 140, but could have gone a little lower and still been happy.
This cooking method is magical because you can't overcook the meat as long as you don't overheat the water.
You may need to research the temperature you want for your particular meat or eating thing. [Eating undercooked foods may be bad for you, may result in blindness, and can cause night sweats if fed to young chickens --Dustin's lawyer]. I find that following the USDA guidelines for cooking temperatures ends with overcooked meat.
Step 3: Season and Seal Your Meat.
Remove meat from any packaging and pat dry with a towel. Salt and season to taste. Seasoning is optional. If you are cooking pork, a two hour brine bath pre sealing is highly recomended. Brine in the bag didn't work as well as I hoped as it resulted in a severe over-brining.
Use your sealing method of choice to remove as much of the air as possible from the bags. They must be waterproof and sink when dropped in water.
Possible sealing methods:
1. Food Saver or similar food sealer. $$$$
2. Ziploc vacuum bags. $ (around $20 for a reasonable supply)
3. Ziploc bag. ¢
For the ziploc bag, slowly submerge the bag and meat into the water to push the air to the top. Seal when just above the water line. Get frustrated. Buy a cheap Ziploc Vacuum Bag.
You need to make sure you have a known maximum thickness of meat in the sealed bag, so don't overlap pieces. Cooking time is based on thickness (see link in step one), so don't overlap pieces. (see photo of how pieces were arranged in sealed bag). These 31.5mm (1.25 inch) steaks took about an hour.
Hint: If your meat is still frozen, put it in the cooler with cold water and a bunch of ice cubes to thaw. You can also just put them in the hot water, but timing the cooking will be harder. If your meat has bones make sure it's well thawed or you will have raw spots unless you keep the meat in the hot water bath for an extra long time.
Step 4: Add Meat to the Water Bath and Maintain the Temperature
Put the bags in the water. Don't let them stack up. Run the bubbler to prevent hot spots or stir often while heating. Close the lid as best you can without crimping the air line all the way or smashing the cords. My cooler lid is a little loose, so I just close it. The seal isn't super important, but it will mean less interruption by the temperature alarm if the water holds its heat longer.
When you add the meat, the temp will drop. Be prepared with some boiling water to top it off, but don't pour it directly on the meat. There are tables online to calculate the exact heat drop, or you can consult your local thermodynamics nerd, or you can just pour hot water in until the temp reaches your target temp again. Your call.
Set the timer and let the meat cook. These steaks took about 1 hour. You can hold beef at the cooked temperature for quite a while before it starts to get mushy (e.g. EWilhelm's 48 hour beef ribs). Some other meats, like fish need to come out right on schedule.
If you don't have an aquarium heater, you can heat water on the stove and add it to the cooler as the water looses temp. This is a little tricky and I have overcooked some meat on accident by overheating the water. If you do this method, try to use as much water as possible by using a large cooler filled up to the brim so you have more thermal mass that cools at a slower rate.
Step 5: Brown the Meat for Serving.
You food is now cooked, but you really need to brown it. It looks much better, but more importantly, browning causes a chemical reaction that is important in the final taste.
You can use a pan, blowtorch or bbq. The pan works the best.
Remove the meat from the bags and reserve the juice. Lay the meat out on a plate and blot dry.
Peanut oil is highly recomended due to it's high smoke point.
Coat your favorite frying pan with peanut oil and put on high heat. Have a pair of tongs and your meat close at hand. Things will happen really fast so try to keep up.
Once oil just starts to smoke, put in as much of the meat as will fit but don't crowd the pan. Brown for just 20 - 30 seconds per side. You don't want to cook the meat anymore. Just brown it and don't burn it.
Remove the the pan from the heat as soon as the meat is done. Because you haven't overshot the temperature, the meat is best served immediately, or wrapped in aluminum foil or other heat-preserving material such as carbonite.
Step 6: (Optional) Make a Sauce.
Making the sauce
Drippings from bags.
Drippings in pan.
About 3/4 cup red wine. (equal to the drippings)
1 tbs flour
Salt, Fresh Pepper, Parsely, Sage, Rosemary and Thyme to taste. (My brother's recipe for Paul Simon gravy)
Put the drippings from the bags in your frying pan. Genltly bring to a boil. Sprinkle in the flour and wisk vigorously. Don't let the flour clump. If you can't get this to work without lumps, wisk the flower into hot water and add the water/flour mixture to the pan while whisking. Add the red wine and continue to whisk while adding spices until it thickens. Remove from heat and serve with meat.
Due to the red wine, the gravy will be a dark purple, so using light colored plates will really make this stand out when served.
Step 7: To Serve and Eat.
Time to enjoy the perfectly cooked steak that you forgot about for a few hours while you re-arranged your cable ties and cleaned out the robot's drive gears. And it still came out perfect. Because Sous-Vide is just that easy.