How to Make It
In a blender or food processor, puree the raspberries with the sugar. Pass the puree though a fine sieve.
In a bowl, whisk the yogurt until smooth and stir in the raspberry puree. Pour the mixture into an ice cream maker and freeze according to manufacturer's instructions. Transfer the frozen yogurt to a container and freeze until firm. Spoon the yogurt into tall glasses, garnish with mint sprigs and serve.