Peel your citrus fruit (I like to cut it into quarters first, so the peel doesn't come off in chunks), and thinly slice them. Put them into a medium-large saucepan, cover with water and bring to a boil. Cook for about 10 minutes.
Add about as much sugar as there is water to the pot - you can eyeball this, or strain the peel in a colander set over a bowl to catch the cooking liquid (if you have a large measuring cup/bowl, even better) and add about as much sugar as there is water. Return everything to the pot, bring to a simmer and cook for about 20 minutes, or until the peel is very tender and almost translucent. If it reduces too much and gets too thick and syrupy, just add more water - aim for tender peel in a thin syrup.
Drain (reserve the syrup for something tasty) and toss the strips in a shallow dish of sugar to coat. Place them on a piece of parchment or foil, or on a rack over a baking sheet to allow the air to circulate around them more. Leave them out for a day or so to dry out a bit, and then store in a sealed container.