2 pounds / 900g Seville oranges
1 lemon and 1 lime (unwaxed)
3 pounds / 1.3 kg granulated sugar
0.5 pounds / 200g jam sugar
2 pints water
Note: for a tarter marmalade, use 3 pounds / 1.3kg sugar.
1. Place the whole oranges and the lemon in a pressure cooker, covering with 1.5 pints water. Cook for about 20-25 mins at pressure. If you don't have a pressure cooker, slow cook them in a low oven for several hours until the skins are soft.
2. Cook the lime separately, for about 30 mins or until the skin is soft.
4. Place the fruit skins on a chopping board and chop into 2-4cm pieces, depending upon how fine or chunky you like your marmalade.
6. Strain out 2 pints liquid, adding water to top it up if needed. Mix the liquid, chopped fruit, and warmed sugar. Bring to a roiling boil for about 20 mins, or until a jam thermometer reads 221 F / 105 C.
7. Remove the pan from the heat. Let stand for 20 mins. Meanwhile, place your sterilised jam pots and lids in a low oven so that they're less likely to crack when you add the hot fruit.