Put the chocolate in a plastic or silicone bowl, (glass or ceramic will get too hot.) Microwave the chocolate like this: 30 seconds, stir. 30 seconds, stir. 15 seconds, stir. 10 seconds, stir. (Remember to stir slowly, fast stirring creates bubbles.)
Take the chocolate’s temperature. It should not exceed 90F for dark chocolate, 86F for milk chocolate, or 84 for white chocolate. If the chocolate has overheated, add 1/4 cup more chopped chocolate and heat 5 seconds at a time, stirring in between, until melted.
Test the temper: put a dollop of the chocolate on a piece of parchment and put it in the fridge. After 5 minutes if it’s solid and snaps when broken in half, your chocolate is tempered. (This step isn’t mandatory, but I like to be sure the temper is correct before using the chocolate.) Do not attempt to keep the chocolate warm by keeping it inside the microwave while you’re waiting for your temper test, it will probably overheat.
Use the tempered chocolate immediately. If using to dip, wrap a towel around the bowl, or put it in a dish of warm water (with a temperature equal or lesser than the tempering temperature) to help keep it warm. If the chocolate cools too much, microwave 5 seconds at a time until usable. If the chocolate solidifies in the bowl, you’ll need to break it into small pieces again before starting the tempering process over.