Scrub the fruit, remove the buttons at the top and put it, whole, into a preserving pan with 2.5 litres water. Bring to the boil then simmer, covered, for 2–2½ hours or until the orange skins are tender and can be pierced easily with a fork.
When cool enough to handle, take the oranges out. Measure and keep the cooking water – you should have about 1.7 litres. Make it up to this amount with more water if you have less, or bring to the boil and reduce if you have more.
Cut the oranges in half and remove the pips with a fork, flicking them into a bowl. Strain any juice from the pips back into the cooking water, then discard the pips.
Meanwhile, cut up the orange peel and flesh into thick, medium or thin shreds. Put the cut-up fruit into the strained cooking liquid. Add the lemon juice and sugar and bring to the boil, stirring until the sugar has completely dissolved. Bring to a rolling boil and boil rapidly until setting point is reached, about 10–15 minutes.
Leave to cool for 10–12 minutes – a little longer if you’ve cut the peel into very chunky pieces – then stir gently to disperse any scum, pour into warm, sterilised jars and seal immediately. Use within two years.
Recipe from Preserves: River Cottage Handbook No2 by Pam Corbin (Bloomsbury, 12.99)