Yields: six 8 ounces/1-cup/250ml jars.
I grew up with the smell of confiture (Preserves) cooking slowly on the stove. We would mainly pick wild fruits such as plums, figs, and rhubarb. Kumquats are these little healthy oranges sweet and sour taste which produces an unusual refreshing flavor. One of those characteristics is that they are winter fruits containing lots of vitamin C. Kumquats can be substituted for Seville / Bigarade / bitter oranges. If so, trim off and discard both orange ends. Cut oranges into quarters, or slices.
Use organic fruits whenever possible. Wash all citrus fruits thoroughly under warm water. For the kumquats: remove stems, cut into four pieces and remove the seeds. For the zests: when removing the skin from lemons and oranges be sure to take off only the thin outer zest or colored portion (leaving the pith on the fruit). The white pith is bitter. If using a vegetable peeler, more of the pith can be removed afterward, then cut into thin strips or use a citrus zester to save time.
Place the prepared kumquats in a large heavy bottom pot or cast iron Dutch oven. Add vanilla seeds and the pods cut in half (each jar should get 2 pieces of vanilla pod). Pour in orange juice and zests. Give a stir and top with sugar without mixing it. Cover and refrigerate for 24 hours.
Bring the mixture to boil and cook on medium heat until it has reached 230ºF/110ºC degrees, if using a candy thermometer. It should take 45 minutes; stirring every so often.To test the marmalade; after 40 minutes or so, place a small bowl over ice water and drop some liquid and wait a few seconds, it should be slightly jelled and will wrinkle a bit when you slide your finger through it. If not, continue to cook. By the time the marmalade is cooking, sterilize jars and lids in a 300ºF/150ºC oven for 20 minutes. Lower temp to 200ºF/95ºC, and leave jars in the oven until the marmalade is ready to be canned.
Remove warm jars from the oven. Carefully, ladle hot marmalade into jars up to the top. Wipe jar rims clean with a damp towel. Place lids on jars, screw on rings. Flip jars and allow to cool for 12 hours at room temp. Store marmalade in a dark and cool place for months or keep refrigerated. Enjoy!