Select thick-skinned oranges. Grate them to remove the rind, then place the oranges in a bowl of salted water and leave to soak overnight.
Rinse the oranges under plenty of running water, then bring to the boil in a saucepan of water. As soon as the water boils, remove and drain the oranges. Cut into quarters or sixths, depending on size.
Place the pieces in a preserving pan, cover with sugar, pour in the lemon juice and cook over a low heat, gently turning the pieces once to avoid damaging them.
Once the oranges are a rich golden colour and the syrup has reduced, remove from the heat and arrange in serving dishes.