(The Art of Italian Cooking by Marcella Hazan)
6 oranges (4 to slice, 2 to juice)
Juice of 1/2 lemon
Zest of 1 lemon, grated
4 Tbsp sugar
Peel 4 of the oranges with a very sharp knife. Remove all the white spongy pulp and the thin skin beneath. Cut the oranges horizontally into thin slices about 1/4-inch thick, removing any seeds. Put slices in shallow serving bowl. Add lemon rind, sugar, and lemon and orange juices. Carefully turn over the orange slices a few times.
Cover the bowl and refrigerate for at least 4 hours or even overnight. Serve chilled, turning the slices just before serving.