Place 2/3 (about 1 cup) of the couverture chocolate to be tempered in a dry bowl (heatproof glass, aluminum or unlined copper).
Melt the chocolate over barely simmering water, less than 140°F (60ºC) with the water not touching the bottom of the bowl containing the chocolate.
When chocolate is melted to 118°F (48ºC) for dark chocolate, or 115°F (46ºC) for milk or white chocolate, immediately remove from the heat. Dry the bottom of the bowl with a towel.
Add the remaining 1/3 chocolate into the bowl. Use a dry rubber spatula to stir and cool down the chocolate until completely smooth and slightly thickened, this is called “seeding”. Be careful not to incorporate air bubbles.
Check the temperature of the chocolate with an instant-read thermometer. When working with the chocolate, the temperature must stay below 90°F (32ºC) for dark chocolate or 87°F (31ºC) for milk or white chocolate.
Repeat the reheating and tempering process to restore the chocolate's fluidity if needed.
It’s best to cool the finished chocolate products in a room at 65ºF (18ºC) or below, temperatures higher than 75ºF (24ºC) will take longer to harden.
Chop couverture chocolate into small uniform pieces if in bar form for even melting.
If melting the chocolate but not tempering for mousses, sauces, beverages or baked goods, melt in the double boiler on the stove top. Alternatively, microwave using 50% power in 15 second intervals. Do not heat chocolate over 120ºF (49ºC).
Do not allow any water to come into contact with the melted chocolate or it will seize up and become clumpy.