Combine sugar and 1/2 cup water in small saucepan.
Cook, without stirring, to 240 degrees on candy thermometer or soft-ball stage.
Cut each orange in half lengthwise; cut each half in thin slices, removing seeds.
Cook orange slices, several at a time, in boiling syrup for 5 minutes.
Remove from syrup with slotted spoon.
Pour remaining syrup over oranges.
Cool thoroughly, garnish as desired.