1/2 lb. fresh ginger, peeled and cut into 1/8-inch-thick slices, preferably on a mandoline
1 cup granulated sugar
Mist a cooling rack with non stick spray and place it on a rimmed baking sheet lined with parchment.
Put the ginger and 3 cups of water in a medium pot over medium-high heat. Cover and cook until the ginger is tender, about 45 minutes. Pour off all but about 1/4 cup of the water, reserving the cooking liquid (see tip below). Add the sugar. Bring to a boil over medium-high heat, stirring frequently. Reduce the heat to medium and cook, stirring frequently (the sugar syrup will thicken as the water evaporates), until the sugar recrystallizes onto the ginger, approximately 20 minutes. Transfer the ginger to the cooling rack, separating the individual pieces
Cool completely, then store in an airtight container.