Finely grate the oranges to remove a thin layer from their peel.
Then quarter the fruit and remove the juicy flesh and fibres from inside, leaving the peel clean.
Roll them up and thread with a thick needle onto a thick white cotton thread, like a necklace, pressing each roll firmly next to the previous one.
Place in a saucepan with enough water to cover them, allow to reach a boil then simmer for 5 minutes. Drain and cover with cold water. Later that day, drain and cover with fresh water, repeating the process 2 more times. The next day, and the day after repeat by draining and covering with fresh water, again twice throughout the day. The reason for this is to draw out the bitterness.
On the fourth day change the water and boil the fruit until well softened (you should find it yielding when pierced with a toothpick). Drain and allow to cool.
Then return the fruit to the saucepan, and stir in the quantity of water and sugar indicated. Leave for around 3 hours until the sugar dissolves, and then boil over high heat for 10 minutes.
The next day, boil again until syrup thickens – check by dropping a few drops of syrup in a glass of iced water; it should form drops before dissolving. Add the lemon juice and bring to the boil again.
Then remove from the heat, allow to cool, and pour into cool, sterilised jars.
20 bitter oranges (Seville oranges)
2½ cups water
2½ tbsps lemon juice