01 - Combine sugar and water in a small saucepan. Heat gently over medium heat, stirring constantly until sugar dissolves completely. Remove from heat and allow to cool to room temperature.
02 - Transfer raspberries to a blender or food processor. Blend until achieving a smooth, uniform puree consistency.
03 - Press the raspberry puree through a fine mesh sieve into a bowl, using the back of a spoon to extract maximum liquid while removing all seeds.
04 - Fold cooled sugar syrup, lemon juice, and raspberry liqueur if using into the seedless raspberry puree. Stir thoroughly until fully incorporated.
05 - Pour mixture into a shallow freezer-safe container and freeze for 1 hour until partially frozen.
06 - Remove container from freezer. Using a fork, vigorously scrape and stir the mixture, breaking up ice crystals thoroughly. Return to freezer. Repeat this churning process every 30-45 minutes for 3 additional hours until sorbet reaches smooth, scoopable consistency.
07 - Portion sorbet into chilled bowls or glasses. Garnish with fresh raspberries and mint leaves if desired.