My Mum had noticed a house with a huge kumquat tree in the front yard, so she knocked on the door and asked to buy some (if I was a teenager I would be like OMG, how embarrassing. Actually, it's embarrassing at any age)! The lady of the house said Mum was most welcome to the kumquats without charge, so Mum happily plucked four kilograms! She gave a kilogram to our Japanese neighbour who eats it fresh, and saved the rest to make jam.
The kumquats need to be washed and soaked for at least 24 hours.The fun part (not) is removing the pips so Mum and I did just that a few weekend ago. Save the pips, wrap them in muslin and cook it with the jam.
It is essential that you make your jam in a clean pot (our pot is for making jam only). The daughter of one of Mum's friend said their home made jam tasted "Chinese", so it's probably best not to use the same pot as the one you've cooked your five spiced stewed pork in. As with making meringues which requires a clean mixing bowl, cut half a lemon and rub all over the inside of your pot for a thorough clean.
Cook 1 kilogram of kumquat with 1 kilogram of sugar and 3 cups of water. The amount of water is the tricky part because we had initially made the jam with 5 cups of water, and since the kumquat was very juicy, the result was very runny jam. If your jam turns out watery, don't trow it out, it's great eaten with plain yoghurt.
Cook the jam under low flame, and patiently stir until it thickens. Pour the jam into steralised jars (wash the bottles and the lids and pop them into the oven for about 15 minutes) ~ the rule of thumb is cold jam into cold jars, and hot jam into hot jars (we always do the hot jar method). Screw on the lid, tip the bottle upside down to cool which creates a vacuum seal. I printed out some labels, and topped the lids with paper doilies tied with red and white bakers twine. Mum dropped off a couple of bottles of the jam to the kumquat tree owner last week.