Add peels to large saucepan and cover with water. Bring water to boil, then drain the peels into a colander and discard boiling water. Return peels to saucepan, cover with fresh water, and bring to a boil again. Drain peels again, then cover with fresh water for a final blanching. Drain peels for final time and set aside.
To make simple syrup: Place 2 cups water in a large pan, add 3 cups sugar and corn syrup, and stir until dissolved. Bring mixture to a boil. Try to avoid stirring too vigorously or splashing, but if crystals form on the side of the pan, remove them with a pastry brush dipped in cold water.
Once the mixture is boiling, add the peels, stirring as little as possible, and simmer until peels become translucent and jewel-toned, usually about 30 to 45 minutes.
Remove peels with slotted spoon or tongs, and drain on wire rack set over a baking sheet. Reserve remaining simple syrup and refrigerate for another use.
Once peels are cool to the touch, fill a shallow bowl with sugar and coat each peel, returning them to the wire rack and straightening them out to dry. Peels can be left to dry for a few hours or overnight.
To coat in chocolate: Melt chocolate in microwave according to package directions. Dip peels in chocolate one at a time, covering bottom two-thirds of the peel and running a spoon along the underside to remove excess chocolate. Place dipped peels on parchment-lined baking sheets.