Use the poaching syrup for brushing cake tiers of the Chocolate Kumquat Cake. These can be prepared up to one month ahead.
Rinse the kumquats, and place them in a large saucepan with cold water to cover. Bring to a boil over medium-high heat. Drain kumquats immediately, and then repeat the process two times, always starting with cold water.
Place the kumquats, sugar, and the 4 cups water in a large saucepan. Bring to a boil. Immediately remove from heat, and allow to cool completely in syrup. Transfer kumquats in syrup to an airtight container and refrigerate until using.