Stab the kumquats 2-3 times with a fork and put into cold water and bring to the boil. Drain and rinse with cold water. Repeat this process twice.
Bring the kumquats to the boil with 180ml water and the sugar. Reduce the temperature and simmer for 15 minutes in an uncovered pan.
Remove the kumquats from the syrup and set aside.
Dice the ginger finely and add the cranberries to the saucepan with the syrup. Cook for 10 to 12 minutes stirring occasionally over a low-medium heat until the cranberries burst and you have a creamy sauce.
In the meantime, cut the cold kumquats into quarters and remove cores. Cut the kumquats into fine strips and add to the cranberries. Store in a tightly sealed container in the fridge.