Ingredients

500g seville oranges
50ml lemon juice
1kg white sugar

Method

1. Weigh the oranges and make a note of the weight, as this will tell you how much of the other ingredients you’ll need, to ensure the marmalade sets well. The basic ratio to follow is: both the sugar and the strained liquid from the sliced and simmered oranges should roughly equal twice the weight of the uncooked whole oranges. So, if you start with 500g whole oranges, after cooking you want to be left with 1L of liquid once the peels have been strained out, and you need 1kg of sugar.
2. Cut the oranges in half and squeeze out the juice. Remove any pips from the juice, spoon any remaining pips out of the peel, place them in a tea cup and cover with water. Then chop the peel into shreds about 0.25cm across and place these in a bowl with the juice and cover with water. Leave both overnight, as this will help the marmalade set well.
3. The next day, place the peel and water in a saucepan. Sieve the pips, place their soaking water (which will have jellied slightly) into the saucepan, then tie the pips in muslin and drop this into the pot. Bring to the boil then simmer for 2-3 hours, topping up with water so that the fruit stays well covered, until the peel is soft when squished between your fingers. Alternatively, cook in a pressure cooker for about 30 minutes.
4. Strain the juice from the peel and measure it. Whatever the original weight of fruit was at the beginning, you want about double that in cooking liquid. If you have more, boil it down in a saucepan to intensify it. If you have less, top it up with water to dilute it.
5. Then add the sugar (double the weight of the oranges), plus 1-2 tbsp brown sugar if you like to make the colour darker. Add the strained peel, plus 50ml of lemon juice for every 500g uncooked whole oranges used. Bring to the boil, skim off any white froth and pips that rise to the surface, and then boil until the temperature reaches 105C.
6. Meanwhile sterilise enough jars in the oven and have the lids washed and ready. When the marmalade reaches 105C, turn the heat off and leave for 10 minutes. Ladle the marmalade into a jug then pour this carefully into the jars, leaving just a bare 0.5cm gap at the top. Screw the lid on tightly and leave undisturbed until completely cold.