In a small bowl, zest lemons. Add sugar to the bowl and use your hands to massage the zest with the sugar. This extracts some of the essential oils in the peel, where much of the flavour is!
Transfer this sugar and peel mixture into a pitcher along with kumquats and use a spatula or spoon to gently crush the kumquats to release more of their juices.
Add water to the pitcher, stir and allow to sit so the flavours can infuse.
Once ready to serve, pour lemonade over ice through a sieve to catch excess zest, top off with a serving of prepared matcha and if desired, a few kumquat pieces for garnish.