In a large 3-quart size saucepan, combine the sugar and cornstarch. Gradually stir in the water until smooth. Bring mixture to a boil over medium heat; cook and stir the mixture for 2-3 minutes, or until slightly thickened.
Add the blueberries and cinnamon stick, return to a boil. After mixture comes to a boil, remove pan from the heat, and stir in 3 tablespoons of the frozen orange juice concentrate; stir until the juice had melted completely.
Place pan back on the stove, cook mixture over low heat for 10-12 minutes; stirring continulously until mixture has thickened up a bit more.
Remove pan from heat, discard the cinnamon stick, cover the pan, and set the pan aside for 30 minutes, so the mixture has time to cool down.
Strain the blueberry mixture through a fine wire mesh strainer, into a heat proof glass bowl, and using the back of a spoon to press out the berry mixture. Be sure to scrape the berry mixture off the back side of the mesh strainer as you go along, and adding it to the bowl. After straining the berry mixture into the bowl, I then covered the bowl with plastic wrap, and placed the bowl in the refrigerator.
Be sure to thoroughly chill the soup (covered) in the refrigerator before serving it. (I refrigerated the soup overnight, and served it the next day.)
Garnish soup with a dollop of Cool Whip (or with Reddi Wip) and fresh mint leaves.
Yields: 3 cups, or 3 servings (1-cup each per serving)