Strange, I could have sworn I posted my recipe last year! Well, perhaps not.
2 kg Seville oranges
2 kg sugar
2 litres water
(Do you see what I'm doing here - so it makes it easy to scale your recipe up or down, depending on time, energy, etc).
Place whole oranges, halved lemons and water in a pressure cooker, and cook at HIGH pressure for 20 minutes. Let cool at room temperature, and wait until cool enough to handle (overnight is good). I've always used a pressure cooker - I believe if you don't you need about 3 times as much water and you need to boil the fruit for about 2 hours, but I've not tried it so can't guarantee it.
Scoop out the insides of the fruit and, if possible, separate out the pips. Chop the rinds into tiny pieces. Put the pips into a small saucepan with some of the water and boil hard for 5 minutes. Strain into the large pan into which you have placed the chopped rinds, the remainder of the water, and the sugar. Heat gently while sugar dissolves, stirring frequently, then bring to boil and boil until setting-point is reached (somewhere between 5 and 10 minutes). Test by dripping on to a cold plate.
Pot into sterilised jars, seal, and keep in a dark place until you eat it.