1. In a small saucepan, combine cornstarch with water; whisk until smooth. Add sugar, lemon zest, juice and egg yolks; cook over medium heat, whisking constantly, until mixture comes to a full boil; cook for 15 seconds. Remove from heat and pour into a large bowl. Let cool slightly. Cover surface with plastic wrap; refrigerate for 2 hours or until chilled. (Recipe can be prepared to this point up to 1 day ahead.)

2. Whisk lemon mixture until smooth. Whisk in yogurt.

3. In bowl, using electric mixer, beat cream until stiff peaks form. Gently fold into lemon-yogurt mixture.

4. Arrange half the berries in six parfait or large wine glasses. Top with half the lemon fool; layer with remaining berries and lemon fool. (Recipe can be prepared to this point and refrigerated for up to 4 hours.) To serve, garnish with whole berries, mint sprigs and grated lemon zest.