Boil the peels in a pot of water for 15 minutes. Drain and rinse well.
Fill the pot with fresh water and add return peels to the pot. Bring to a second boil for 15 minutes. Drain and rinse well, set aside.
Fill the pot with 1 cup of fresh water and add 2 cups of sugar. Bring to a boil, stirring until the sugar is fully dissolved.
Add citrus peels and reduce the heat, simmering for 20 minutes or until the peels become translucent and the mixture thickens into a light syrup. Prepare a bowl of the 1 cup of sugar and set aside.
Using a slotted spoon, remove the peels in small batches and allow the extra syrup to drip off before tossing in the bowl of sugar to coat. Make sure to do this while the peels are still hot. Reserve the syrup to use as a simple syrup for drinks!
Put a single layer of the peels on a wire rack until completely cooled and dried, usually overnight or 1-2 days. Gently shake off excess sugar before storing it.
Store in the fridge for up to three months, or six months in the freezer.