1) Using a vegetable peeler, cut the orange part of the peel, from the stem end of the orange down to the navel end, forming long 2 to 2 1/2-cm-wide strips.
2) Bring a heavy small saucepan of water to a boil. Add the peel and cook for 1 minute. Drain and then rinse the peel under cold water. Repeat, cooking the peel in the saucepan with fresh boiling water and rinsing under cold water.
3) Stir the sugar and 120ml of fresh water in a heavy small saucepan over medium-high heat until the sugar dissolves. Bring to a boil. Add the orange peel and simmer over medium-low heat until tender, about 15 minutes. Using tongs, transfer the peel to a sheet of parchment paper to dry slightly, about 1 hour.
4) Line a small baking sheet with parchment paper. Stir the chocolate in a small bowl set over a saucepan of simmering water until it's melted and smooth. Dip 4cms of each candied orange peel into the chocolate, then place them on the prepared baking sheet. Refrigerate until the chocolate is set, about 15 minutes.