Simmer The Kumquats: Combine sugar and water in a medium saucepan and bring to a boil over medium-high heat. Add the kumquats, cinnamon, and vanilla bean and seeds, reduce the heat to medium-low and simmer until fruit has let off liquid and the skins are knife tender, about 15 to 20 minutes.
Steep The Kumquats: Remove saucepan from the heat and set aside until the fruit and simple syrup are room temperature and the cinnamon and vanilla flavor are apparent, about 2 to 4 hours.
Strain the fruit from the syrup and cook the syrup over medium heat until it is reduced and thickly coats the back of a spoon, about 10 minutes more. Pour the syrup over the fruit and spices and use or store refrigerated in an airtight container until ready to use.