Cool strawberry soup

Place strawberries and orange juice in a blender, cover, and process until smooth. Pour fruit mixture into a saucepan and whisk in cornstarch. Place over medium-high heat and cook, whisking periodically, until the mixture comes to a boil. Reduce heat to low and cook for 1 minute, whisking constantly. Remove pan from heat and let cool 5 minutes. Whisk in NutraSweet and yogurt. Pour soup into a shallow container and refrigerate for at least 2 1/2 hours to allow for thorough chilling and blending of flavors. If desired, thin soup slightly with cold water before serving. Serve in bowls and garnish each serving with a whole strawberry and two vanilla wafers, if desired.