Chop 1 pound of chocolate into matchstick-size pieces on a dry cutting board with a chef’s knife, reserving one piece of chocolate that weighs approximately 1 ounce. (If tempering 8 ounces of chocolate, reserve a ½-ounce piece of chocolate; if tempering 3 pounds of chocolate, reserve a 3-ounce chunk, etc.) Place the chocolate pieces in a bowl that fits snugly over another saucepan or bowl (a double boiler is fine too) half filled with water no hotter than 120 degrees. As the chocolate melts, the water will cool, so be prepared to replace the water occasionally. (After melting chocolate several times, you’ll become accustomed to the feel of 120-degree water, thus eliminating the need to check it with a thermometer.)