01 - Combine sugar and water in a small saucepan. Heat over medium heat, stirring constantly until sugar dissolves completely. Remove from heat and let cool to room temperature.
02 - Blend raspberries in a food processor or blender until completely smooth. For seedless sorbet, press puree through a fine-mesh sieve into a bowl, discarding the seeds.
03 - Whisk lemon juice and cooled syrup into raspberry puree. Add lemon zest if using and stir until thoroughly incorporated.
04 - Pour mixture into ice cream maker and churn according to manufacturer's instructions for 20-25 minutes until thick and slushy. Alternatively, freeze in a shallow container, raking with a fork every 30 minutes for 2-3 hours until smooth.
05 - Transfer churned sorbet to an airtight container. Freeze for at least 2 hours until firm enough to scoop.
06 - Scoop into chilled bowls or cones. Garnish with fresh raspberries and mint leaves if desired.