Add all ingredients except the soda to a shaker and fill with ice.
Shake, and strain into a Collins glass.
Top with soda and garnish with half a kumquat.
.5 pounds Kumquats, halved
4 oz Sugar
12 oz Japanese apple cider vinegar
Place the kumquats and sugar in a mason jar. Let it macerate for two days in the refrigerator. Add the vinegar to the mixture and and let sit for two more days in the refrigerator. Squeeze the kumquats and strain.