1kg oranges (approximately 5 large oranges)
400g lemons (approximately 3 large lemons)
3 cups Chelsea Jam Setting Sugar, approximately

Remove zest from oranges and lemons and slice finely. Remove white pith and discard.
Chop orange and lemon flesh coarsely. Place orange and lemon zest and flesh in a large heavy-based saucepan and just barely cover with cold water. Bring to a boil and simmer for half an hour, or until zest is soft to your liking.
Leave fruit to cool slightly, then transfer to a bowl. Measure the fruit back into the saucepan and add an equal quantity of Chelsea Jam Setting Sugar. Bring to the boil, stirring until sugar dissolves. Boil for 4 minutes then test for set by spooning a little onto a plate – if a film forms on the surface, it is ready.  If using a sugar thermometer, the setting point is 105˚C.

Spoon or pour jam into clean sterilized jars and cover with lids.