How to Make It
Lightly scrape outer skin of kumquats with blade of a knife to release citrus oils. Cut kumquats into thin slices.
Combine kumquats, water, and soda in a flat-bottomed kettle; bring to a boil. Reduce heat; cover and simmer 15 minutes. Set aside to soak overnight. (Do not drain.)
Strain kumquats through a damp jelly bag or 4 layers of cheesecloth, reserving 3 cups juice. Discard pulp.
Combine reserved juice and sugar in kettle; bring to a rolling boil, stirring constantly. Boil, stirring frequently, until mixture registers 220° on a candy thermometer or until mixture sheets from a cold metal spoon. Remove from heat, and skim off foam with a metal spoon.
Quickly ladle jelly into hot sterilized jars, leaving 1/4-inch headspace. Cover with metal lids, and screw bands tight. Process jelly in boiling-water bath 5 minutes.
Oxmoor House Homestyle Recipes