Select 3 large navel oranges. Zest the peel from one orange or about enough for four teaspoons of zest. Set the zest aside. Pour one cup of water into a saucepan and stir in one cup of sugar. Bring the sugar water to boil over medium high heat. Boil for five minutes. Add 1 teaspoon of vanilla and the orange zest. Stir in to mix. Continue to boil the mixture for an additional 5 minutes. Meanwhile peel all the oranges removing pith as well. Slice the oranges horizontally into 1/8″ to 1/4″ slices. Place half the slices into a flat dish and pour half the syrup over the slices. Put the remaining slices on top and pour remaining syrup over those slices. Chill for several hours or overnight. Arrange on plate and serve. Serves 4-6.