Thoroughly clean the oranges under running water using a vegetable brush to remove any residue.
Slice a thin piece off the top and bottom of each orange, then make four vertical cuts through the peel down to the white pith, taking care not to cut the flesh.
Peel off each section of the orange peel and cut into strips about 1/4 inch wide.
Place the peel strips in a pot and cover with an inch of water. Bring to a boil and then drain; repeat this boiling and draining step one more time.
Return the orange peel strips to the pot, add 2 cups of water, 1 cup sugar, and the vanilla bean if using. Bring to a boil again, then lower the heat and simmer uncovered for 30 to 35 minutes until the peels become translucent and the syrup reduces.
Turn off the heat and let the peels sit in the syrup for about 5 minutes to absorb more sweetness.
Using tongs, transfer the peels onto a rack set over parchment paper to dry. Allow them to dry for at least 8 hours, or ideally overnight for up to 24 hours.
Once dried, toss the peels in additional granulated sugar and, if desired, dip them in melted chocolate then cool until set.
Serve the candied orange peels immediately or keep them fresh in an airtight container refrigerated for later enjoyment.
