2 cups water
1 cup sugar
2 cups orange juice
2 teaspoons finely grated orange peel
1 teaspoon lime juice, optional
1/2 teaspoon pure Vanilla extract
In medium sized pan, or in microwave (in microwave-safe bowl), bring sugar and water to a boil.
Add grated orange peel, and let sit to cool.
Stir in orange juice, lime juice, and vanilla.
Pour into ice cream freezer container, and freeze according to manufacturer's directions, or
Simple method:
Pour into metal cake pan, cover, put in freezer until slushy, and outer edges are frozen, (at least 2-3 hours).
Break up into chunks, stir and serve.