Cut off the bottom of all the fruit so they can stand on their own. Make 5 cuts in the peel from top to bottom at regular intervals but do not cut into the fruit itself.
Remove the skin, taking care to remove as little of the white pith as possible. Cut the peel into thin strips.
Place the peel in a saucepan, cover with cold water and bring to the boil over high heat. Drain and repeat this process twice, using fresh water each time. This removes the bitterness. Drain well in a colander.
Add sugar and water to the saucepan and whisk to combine. Bring to the boil and cook for 8 to 9 minutes. Add the peel, reduce heat and simmer for 45 to 60 without stirring, otherwise the sugar will crystallise around the peel.
Once the peel is shiny, drain (reserve the sirup for another use) and place on a wire rack. Let cool and harden for 4 to 5 hours, then store in a airtight container.