Place all ingredients, except the orange slices, in a blender and puree until smooth and creamy. Pour into glasses or tumblers. Slit the orange slices half way to the center. Garnish each glass with a slice of orange on the rim.
Per serving - 259 calories, 6 gram fat (18% calories from fat), 12 gram protein, 44 gram carbohydrate, 5 gram fiber, 0 milligram cholesterol, 113 milligram sodium