PREPARATION:

1. Combine strawberries, powdered sugar, water, sugar substitute and 1 tablespoon lemon juice in blender. Process until smooth. If necessary, add additional 1/2 tablespoon lemon juice.
2. Pour into 8-inch square baking pan. Cover with foil and freeze 2 hours or until slushy. Remove from freezer and stir to break mixture up into small chunks. Cover and return to freezer. Freeze 2 hours, then stir to break granita up again. Cover and freeze at least 4 hours or overnight.
3. To serve, scrape surface of granita with large metal spoon to shave off thin pieces. Spoon into individual bowls and top each serving with 1 tablespoon whipped topping, if desired. Serve immediately.