This recipe makes a large blender-full, but if you don't have a large enough blender, just do it in batches and dump it in a large pitcher for the final stirring. (Or just make half the recipe!)
1 12-oz. can frozen orange juice concentrate
2 cups milk
2 cups water
1/2 cup sugar
2 tsp. vanilla
24 ice cubes
Optional: apricot nectar, frozen berries, mango, other fruits/syrups/jams
Mix all in blender until slushy. Stir again before serving.