12 kumquats
1 orange, pips removed
800g (2 lb) caster sugar, or as needed
1 lemon, juiced
2 ltrs (3,5 pints) water, or as needed

Finely chop the kumquats and orange and combine. Using a mug, measure them into a large pot. Add 3 mugs of water per mug of fruit. Leave to stand in a cool place for 12 hours, or overnight. After soaking, transfer to a pan and bring the fruit mixture to the boil, reduce heat and simmer until the rind is very tender. Remove from heat, and measure cooked fruit. Add one mug of sugar to the pot per mug of the fruit mixture. Finally mix in the lemon juice (approx. 4 tablespoons).
Return the fruit to the pan, and bring to the boil once again. Boil, stirring occasionally, until the thickened stage is reached. The temperature of the marmalade should be about 105° C (220° F) when checked with a kitchen thermometer. Remove from the heat, and skim any foam from the surface. Transfer the mixture to sterile jars, leaving a bit of headspace, and seal immediately. Process any unsealed jars in a water bath. Refrigerate after seal has been broken.