1. Using a sharp knife, cut lemon into thin slices; discard seeds.
2. Prepare an ice-water bath; set aside.
3. Bring a medium saucepan of water to a rolling boil. Remove from heat, and add lemon slices and stir until softened, about 1 minute. Drain, and immediately plunge slices into ice-water bath. Drain.
4. Bring 1 cup sugar and 1 cup water to a boil in a medium pan, swirling to dissolve sugar. When liquid is clear and bubbling, reduce heat to medium-low. Add lemon slices, arranging them in one layer with tongs. Simmer (do not let boil) until rinds are translucent, about 1 hour.
5. Transfer to a baking sheet lined with parchment. Let cool until room temperature.
6. Sprinkle granulated sugar (I prefer organic cane sugar) on one side of the lemon slices. Turn slices over and sprinkle other side with sugar.
They can be left in rings, or sliced to make wedges.