Wash the kumquats well and remove the stems. Slice each kumquat into 4 or 5 slices and remove the seeds.
Boil the sugar and water, then add the kumquats. Simmer for about 20 minutes over low-medium heat.
Once they've softened, turn off the heat, then let sit as-is overnight. Don't use a lid so that moisture can evaporate.
The kumquats will sink when they absorb the sugar well. Heat again to preserve it.
Once it begins to boil, immediately turn off the heat and add the Cointreau.
Transfer into containers while still hot, soaking in the syrup, and store.
It's also delicious when used right away. The syrup is delicious as well.
Story Behind this Recipe
I wanted to come up with a delicious way to eat and store kumquats.
Be careful not to over-heat it so that it retains the color and fragrance. By not using high heat, the kumquats will turn out soft. Add the Cointreau at the end in order to retain the fragrance and for storage.