Inspired by some of the more technical Sous-Vide hacks, I decided to give sous-vide cooking a shot to see if the results are truly as incredible as described, before committing to buying some better equipment.
For the uninitiated, sous vide cooking uses a water bath at a constant and precise temperature to cook meats/veg/whatever for long periods of time in a vacuum sealed bag. This allows the entire slab of fish/meat to reach the perfect level of done-ness from edge to edge, without overcooking any part of it.
Professional sous vide machines cost about $1000, whereas portable immersion circulators which you stick into an existing pot will still cost $200-300. This hack uses nothing but a $3 styrofoam box and an electric kettle, and produced the best salmon we've ever made or eaten at any restaurant, and by a large margin at that!
The basic principle was just to replicate sous vide cooking by manually maintaining a constant temperature water bath in a styrofoam cooler box, for as long as you need to cook. We chose salmon as our first experiment, since it cooks relatively fast (30 min at 50-55 deg C) compared to a steak (at least 1 hr).
Check out this sous vide time and temperature guide from Chef Steps for a handy printable reference. And you can bet those food science geeks at Chef Steps have already done all the testing needed for this to be spot-on!
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Step 1: Brine the Salmon
We soaked the salmon steaks in a large bowl of water with some dissolved salt beforehand. 1-2% salt by weight compared to the total weight of the water+meat is about right. Leave to brine in the fridge for 30min-1hr.
This apparently seasons the salmon, and also helps to prevent white albumen from leaching out of the fish during the cooking process.
Step 2: Prep the Water Bath
Fill up the styrofoam box with hot water, making sure you get the water to about 1-2 degree above your final desired temperature. This is to allow for some cooling to take place when you put in the cold meat. We used a digital thermometer to check the water temperature.
Step 3: Bag the Salmon
The fancy versions use a vacuum sealer and custom bags. We just used a regular food-grade ziplock with a double zip. Does the job.
Pop in the fish into a ziplock bag, along with a good helping of olive oil, maybe butter. We added rosemary as well. No salt as that will draw moisture out of the fish. Season it later!
Close the bag almost all the way, leaving a little corner open. Next slowly immerse the bag into the water bath, letting the water pressure squeeze all the air out of the bag. Seal the remaining corner tight.
Submerge the bag and check the temperature again. Top up with hot water if needed.
Cover up the cooler box and wait! Check back every 10 min or so to see if the temperature has dropped too much. The idea is for the entire piece of fish to reach equilibrium, at whatever temperature you have predetermined will give you your ideal cooked texture. 50 degrees Celsius will give you a silky smooth texture, slightly rare. We went for 55 deg as we wanted it just medium-well through and through.
The beauty of sous vide cooking is that it can stay in the water bath much longer if needed, and it won't overcook as there is no way the fish/meat can reach any higher temperature than what you have set. For fish the maximum recommended time is 1 hr.
Step 4: Sear and Enjoy!
After 35 min or so we unbagged the fish, and seared the skin side ONLY on a hot hot pan with some olive oil. I only gave it 30 sec on the pan to avoid overcooking the fish, but it could have gone a little longer to let the skin crisp up.
Season with pepper and salt and serve. (It is already slightly salty from the brining, so go easy on the salt.)
Enjoy! This was by far the juiciest and silkiest salmon steak we have ever had. No hard overcooked fish on the outside, nothing raw and under-done on the inside. Every bit perfect!
Step 5: Sold on Sous Vide!
Conclusion: We're sold on sous vide cooking. Amazingly simple and scientifically consistent results, even with our styrofoam box hack.
We gave sous-vide eggs a shot as well, and the eggs came out perfectly poached with creamy yolks and soft runny whites at 63 deg C for an hour. And eggs don't even need any plastic bags - just dump the egg (in its shell) into the water bath. Perfect for catering a brunch with friends, cuz you don't need to fuss over timing the eggs to perfection.
So we've gone ahead and bought a $23 electronic temperature controller that promises to convert any analog crockpot into a sous vide machine. http://www.ebay.com/itm/141553021483It's a great find recommended by maozai83 in the comments section of this other awesome instructable: https://www.instructables.com/id/Sous-vide-cooker-f...
I'll post some updates once we receive it!
UPDATE: I've received my electronic temperature controller and tested it out with my analog crockpot and it works great as a sous vide machine. (See photos) There is a bit of temperature fluctuation to be expected when using a crockpot, up to +- 0.5 deg (C) on 'low''. This is because the latent heat in the crockery continues to heat up the water after the heating coils are turned off, and it continues to cool down for a little bit even after the heating coils are turned on again. However, that's more than good enough for my purposes as a home cook. 63 degree eggs turned out perfectly runny, 64 degree eggs turned out with a nice yolk that barely holds together, and 55 degree salmon was lovely, although it could benefit from a couple of degrees less heat for a creamier texture. All in all, not bad for a $23 gadget!