Sous-vide:
Already tempered chocolate doesn’t need to be tempered if you don’t get it any hotter than around 91°F / 32.8°C. The desirable forms of fat won’t melt, so you’re good to go. To melt already tempered chocolate, seal it in a vacuum bag and submerge it in a water bath set to 91°F / 32.8°C. (You can go a degree or so warmer; experiment!) Once it’s melted—which might take an hour or so—remove the bag from the water, dry the outside, and snip off one corner: instant piping bag.
Melt the chocolate at 122 F and then change the bath temp to ~90 F and let it sit for 12+ hours.
This makes the process even more hands-off, although it does mean planning ahead.
Also avoids the low-temp limitation on the sous-vide supreme (won't go down to 81)
https://www.guittard.com/in-the-kitchen/article/tempering-chocolate
http://food52.com/blog/3601-how-to-temper-chocolate
Tempered chocolate has a shiny, glossy appearance, will snap when you break it, and, most importantly, won't melt when you touch it. Scientifically, tempering chocolate means aligning the cocoa butter crystals so that they're stacked tightly together. In the kitchen, it means heating up your chocolate to reach a desired temp, cooling it down slightly, and stirring it like mad (agitating, in pastry school terms) the entire time.
Let's begin. Start with 1 pound of already-tempered dark chocolate (chocolate you buy from the store is already tempered). Put a third of the chocolate aside. Place the other two-thirds of the chocolate in a clean dry bowl over a pot of simmering water (a double boiler). Some chocolatiers prefer to stray away from metal bowls, opting instead for a material that doesn't conduct heat as quickly.
Using a chocolate thermometer, heat the chocolate to 115 degrees. You can also heat the chocolate in a microwave in 5-10 second spurts if you do not have access to a double boiler. Be careful not to let the chocolate get too hot -- the temperature of chocolate rises quickly. If you go over 120 degrees, your chocolate will burn and you will have to start over with a new batch (so sad).
Once your thermometer reads 115 degrees, remove the chocolate from the heat and place it on a damp towel “nest” on a flat secure surface. This damp towel will stop the bowl of chocolate from moving while you stir and will also soak up any condensation on the outside of the bowl (which can cause seizing when making contact with chocolate).
Make sure your remaining third of chocolate is broken into little pieces. Put most of this chocolate into the heated chocolate and stir until all pieces are melted (remember: agitation). Once all the new pieces are melted, continue to add the rest of the chocolate little by little, stirring in between each addition. The closer you get to 90 degrees, the more you will notice the chocolate changing in thickness and texture. You may reach 90 degrees before you use all of the broken-up chocolate -- that's okay.
To test: Stick the end of a spoon in the chocolate and drizzle it onto a piece of parchment paper. Place it aside to sit at room temperature. If, after 2 to 3 minutes, you see it start to lose its sheen and harden…your chocolate is tempered! You are ready to start molding or dipping.
Your chocolate will hold at 88-90 degrees for a few minutes, but once you go out of temper you must start all over again. You can maintain the chocolate by keeping it in a proofer set at 90 degrees (or sometimes putting the bowl back on the double boiler for a second or two will do the trick). Do not walk away. A second too long, and your chocolate will spike in heat -- and you will need to start again.
If your test is not drying you may need to cool further, or add more broken-up chocolate and continue to stir. If this still doesn’t work, you may not have stirred enough when adding the broken-up chocolate -- try reheating the mixture and start over.
Dark Chocolate: 114-118° F (46 – 48° C)
Milk Chocolate: 105-113° F (40 – 45° C)
White Chocolate: 100-110° F (37 – 43° C)
Note: be very careful as the high milk and sugar content in white chocolate will cause it to burn easily.
Dark chocolate should be between 88-89° F (31° C)
Milk and white chocolates should be between 84-86° F (29 – 30° C)
Let's get dipping:
Food 52 (http://s.tt/1zoE4)