01 - Combine sugar, water, and salt in a small saucepan. Heat over medium, stirring until sugar fully dissolves, about 2–3 minutes. Remove from heat and allow to cool to room temperature.
02 - Stir lemon juice, zest, and vodka if using into the cooled syrup mixture.
03 - Pour mixture into an ice cream maker and churn according to manufacturer’s instructions until thick and creamy, approximately 20–25 minutes.
04 - Transfer sorbet to a freezer-safe container, cover, and freeze until firm, at least 4 hours.
05 - Remove sorbet from freezer and let stand at room temperature for 5 minutes before scooping and serving.