8 medium navel oranges, preferably organic, quartered lengthwise
5 1/2 cups granulated sugar
1/4 cup light corn syrup
In a large saucepan, cover the oranges with water and bring to a boil. Reduce the heat and simmer for 30 minutes. Using a slotted spoon, transfer the oranges to a baking sheet lined with parchment paper. Pour off the water.
In the same saucepan, combine 4 cups of the sugar with the corn syrup and 2 cups of fresh water and bring to a boil over moderately high heat; stir constantly until the sugar is dissolved. Add the oranges and cook over low heat, stirring once or twice, until they begin to look glassy, about 1 1/2 hours.
Raise the heat to high and boil vigorously for 7 minutes; the rinds will begin to look translucent. Remove from the heat and let the oranges cool in the syrup. Using a slotted spoon, transfer the oranges to a baking sheet lined with parchment paper. Let the oranges stand uncovered overnight or until tacky to the touch. Reserve the cooking syrup.
Bring the syrup to a boil over high heat. Add the oranges and boil for 10 minutes. Let cool completely in the syrup. Using a slotted spoon, transfer the oranges, skin side down, to a rack. Let stand until tacky.
Put the remaining 1 1/2 cups sugar in a paper bag, add the oranges and shake until well coated. Dry the oranges on a baking sheet lined with parchment; sugar them again if they still seem moist. Let the oranges stand uncovered overnight or for several days.
The oranges can be stored in an airtight container for up to 1 month.
These succulent oranges can be served on their own as a sweet or chopped and used in other desserts.