01 - Combine water and sugar in a small saucepan. Bring to a gentle boil over medium heat, stirring constantly until sugar completely dissolves, about 2–3 minutes.
02 - Remove saucepan from heat. Add fresh mint leaves and let steep for 10 minutes to allow the mint flavor to infuse into the syrup.
03 - Strain out the mint leaves using a fine mesh strainer. Allow the mint-infused syrup to cool completely to room temperature.
04 - Whisk together the cooled mint syrup, freshly squeezed lemon juice, and grated lemon zest in a mixing bowl until fully incorporated.
05 - Pour mixture into an ice cream maker and churn according to manufacturer's instructions, typically 20–25 minutes, until the mixture reaches a thick, slushy consistency.
06 - Transfer churned sorbet to a freezer-safe container. Cover tightly and freeze for at least 4 hours until firm enough to scoop.
07 - Scoop sorbet into chilled bowls or glasses. Garnish with fresh lemon slices and mint sprigs if desired. Serve immediately.