Cumquat marmalade is my favourite, so I usually try to make a few jars each year. Can you even buy cumquat marmalade from the supermarket? I've certainly never seen a cumquat in the produce section of the supermarket - you have grow them yourself or know someone who grows them - so it somehow makes this marmalade all the more special I think.
As usual, making the marmalade involved consulting numerous cookbooks for a recipe. So, based on the combined wisdom of Cookery the Australian Way, The PWMU (Presbyterian Women's Missionary Union) Cookbook, Stephanie Alexander's The Cook's Companion and In The Kitchen by Allan Campion & Michele Curtis (if I could only have one cookbook, this would be the one), this is the method I used. (Which has resulted in near perfect marmalade in my personal opinion.)
Start with a large bowl of cumquats.
Slice the skin off 4 sides and the top and bottom of each cumquat leaving the centre pith and pips behind (I decided this was easier than halving or quartering them and then cutting out the pith and pips as most of the recipes seem to suggest).
Weigh the skins and note this down (I had 800g). Place in a large saucepan and add cold water until just covered. Leave to soak overnight.
Place the cubes of leftover flesh & pips in a separate bowl and also cover with water (this is to extract the pectin from the pips so the marmalade will set). Leave to soak overnight.
The next day, strain the liquid from the flesh & pips and add this liquid to the skins. For good measure (to really make sure I had maximum pectin!), I then put the flesh & pips in a sieve and placed it in the saucepan so it was just sitting in the liquid but not spilling out.
Simmer the skins for 30 mins until soft and translucent (then remove the sieve). Add an amount of sugar equal to the weight of the skins (in my case, 800g). Simmer for approx 20-30 mins until the marmalade reaches setting point (testing a small blob on a cold saucer).
Pour into sterilised jars. (Makes about 4 jars.)