One of the quickest ways to ruin a bowl of matcha is to treat it like black tea. Boiling water scorches the delicate leaves, releasing excess bitterness and astringency. You want water that's just off the boil—around 160–175°F (70–80°C). If you don't have a thermometer, let a full kettle sit for two to three minutes after boiling. The difference in sweetness is dramatic.