Preheat oven to 135° F (57.22° C).
Line a baking sheet with parchment paper.
Using a mandolin, slice the oranges in ⅛" slices.
Place slices in single layer on lined baking sheet, and put in oven for 4 hours.
Flip slices about halfway through.
Remove when slices are dehydrated and no moisture remains.
If leaving plain, place in an airtight container and store in a cool dry place. Or if dipping in chocolate, refer to instructions below.