Fill a large bowl with ice water and set aside.
Bring 4 cups of water to a boil in a large saucepan. Add orange slices and boil for 2 minutes.
Transfer slices immediately to the ice water bath. Discard the boiling water.
In the same saucepan, combine remaining 4 cups water and sugar. Bring to a boil, stirring until dissolved.
Reduce heat to medium low and add the orange slices. Simmer for 45 to 60 minutes until rinds appear translucent. Gently swirl every 15 minutes.
Transfer slices to a wire rack set over a baking sheet. Arrange in a single layer.
Let dry up to 24 hours until no longer wet.
Optional: Dip in granulated sugar or melted chocolate before serving.
