We've been very lucky this year. Our kumquat trees have produced a bumper crop. Yesterday, the girls brought me a huge bucket filled with beautiful kumquats. When I tasted them, I found them a bit sour, so I decided to make a nice batch of marmalade.
As a child, I ate a ton of marmalade on my vacations to Great Britain, but I have to say the best marmalade I've had is made by husband's friend Laura. She adds a dash of vanilla extract to her marmalade which I think really brightens and accents the citrus flavor. She also makes great homemade vinegar.
Squeeze the limes. Gather the juice and pulp.
Wash the kumquats and thinly slice them using a sharp chef knife. Discard all the seeds and the white center membrane.
Place the sliced kumquats, lime, water and sugar in a pot. Bring to a boil, then lower the heat to a medium low and cook for 15 minutes. Remove from the heat. The content should be syrupy. Cover, set aside and let it sit overnight (at least 18 hours) at room temperature.
The following day, bring the kumquat syrup to a boil, then reduce a simmer for one hour. Stir every now and then using a wooden spoon. Bring back a boil. Skim any foam that develops on the top before pouring into the Mason jars. Add the vanilla extract.
Fill a big pot of water and bring to just under a boil. Place the Mason jars, lid, heat-proof funnel and tongs in the pot and let it boil for 10 minutes. Be sure to read the instructions that come with your Mason jars. They'll give you exact time and techniques.
Remove the jars from the water and fill with kumquat marmalade leaving about a 1/4-inch head space or whatever your canning directions say. Carefully place the lid on the jar. Tighten the collar around each jar. Bring your big pot of water to a boil and place all the sealed jars in it for 10 minutes.
Remove the jars from the water. If the top of the lid still pops, the vacuum didn't form and you'll need to consume the product in the next couple of weeks, storing it in the refrigerator. Otherwise you can store it in your pantry for up to a year.
This is a tartine (toast in French) made out of brioche that I slightly toasted and spread with butter and kumquat marmalade.
To insure a good sterilization of the product, I stack a dozen magnets together to create a stick and use it a gripper to place the lids on the jars without touching them. Just make sure the magnets are clean!
The next day, when you bring the marmelade back to a boil after simmering for an hour, your candy thermometer should read 220°F.
Another test is to place a drop of the syrup on a cold plate. After it cools down (2 minutes), if you tilt the plate and it stays in place, it's time to put the content in jars.
The marmalade will taste better if you let the sealed jar sit for at least a week before opening.