Since this recipe has no added pectin, it's a bit softer than store-bought marmalade. I love it spread on think slices of toast or spooned into yogurt or müsli. Make sure to choose kumquats that are quite firm, not squishy. —quiltedgiraffe
Prepare the kumquats 8 - 12 hours before you wish to cook the marmalade. Wash them well. Slice the stem end of the kumquats off and discard. Then slice each kumquat in half lengthwise. (Use a sharp paring knife!) Remove the seeds and any thick white pith from the center, saving in a small bowl. You will extract the natural pectin from the seeds and pith Then, thinly slice each kumquat crosswise. Mix the kumquat halves with the sugar. Cover and let sit for 8 - 12 hours, stirring every so often if convenient.
When you are ready to make the marmalade, place the reserved pith and seeds in a square of cheesecloth and securely tie the bundle with kitchen twine. Do the same thing with the tea. Place the bundles in a saucepan with 3 cups of cold water. Bring to a boil, and let simmer for 20 minutes. Then remove from the head and let sit until cool enough to handle. Squeeze any liquid from the tea leaves back into the pot. Reserve. Take the membrane bundle and squeeze all the pectin into the bowl with the kumquat slices.
Measure the reserved tea liquid, and add enough water to bring back to 3 cups. Pour the tea into a large pot. Add the kumquats and the juice of 2 lemons. Bring to a boil and let simmer until desired consistency (or until the marmalade reaches 221°. (To test consistency, spoon a bit onto a chilled plate.)
Once the marmalade is thick enough (remember it will thicken slightly as it cools) pour into sterilized jelly jars. Process in a water bath, if desired.
(Note: I learned how to make jam in Europe, where they do not use water baths. I pour the hot jam into jars until just below the rim, screw the lids on tightly, and then turn the jars upside down until cool. They seal every time, and I have never had any problems.)