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1
Slice the kumquats in half and remove the seeds and the tough white center membrane.
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2
Try to leave as much flesh as possible lining the peel.
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3
In a large heavy- bottomed pot, mix the kumquats, juice of 1/2 lemon, water and sugar. Bring to a boil, then reduce heat and simmer for about 15 minutes.
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4
The liquid should be syrupy. Cover and leave to steep overnight.
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5
The next day, bring the mixture back to a boil. Add the vanilla extract.
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6
Lower heat, and simmer for about an hour, stirring periodically and removing any foam with a spoon.
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7
Check the temperature regularly with a candy thermometer - when the mixture reaches 220 F, it's ready.
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8
The marmalade will seem runny, but will thicken up quite a lot when it cools.
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9
To test whether it's ready, chill a plate in the freezer for a few minutes.
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10
Place a few drops of the marmalade on the chilled plate. If the marmalade thickens to a jam-like consistency, it's ready.
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11
Now you need to jar the jam.
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12
While the marmalade is simmering, bring another large pot of water to the boil.
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13
Boil the jars and their lids for about 10 minutes. Remove with a pair of tongs (also sterilized), and place on a clean kitchen towel.
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14
When the marmalade is ready, pour into the jars, leaving a little air at the top of the jar.
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15
Put the lids on and tighten. Place the closed jars upright into the pot of hot water, ensuring that water covers the lids.
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16
Boil for 10 minutes. Remove (carefully! They will be hot) and let cool.
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17
The seal at the top of the jars should be vacuumed down (they should not pop when you press on them).
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18
If the jars sealed correctly, the marmalade should keep without refrigeration for a year.
