01 - Combine sugar, water, and salt in a small saucepan. Heat over medium heat, stirring continuously until the sugar fully dissolves, about 2 to 3 minutes. Remove from heat and cool to room temperature.
02 - Incorporate lemon juice and lemon zest into the cooled syrup. Add vodka if desired and mix thoroughly.
03 - Pour the mixture into a shallow dish or bowl and refrigerate for at least one hour until thoroughly chilled.
04 - Transfer the chilled mixture to an ice cream maker and churn according to the manufacturer's instructions, typically 20 to 25 minutes, until it attains a soft sorbet texture.
05 - Place the churned sorbet in an airtight container and freeze for a minimum of three hours or until firm.
06 - Allow sorbet to soften at room temperature for five minutes before scooping into bowls or glasses.