01 - Combine sugar and water in a small saucepan. Bring to a gentle boil, stirring continuously until sugar completely dissolves. Remove from heat immediately.
02 - Add fresh basil leaves to the hot syrup. Cover saucepan and let steep for 15 minutes to extract herbal essence.
03 - Pour syrup through a fine mesh sieve to remove basil leaves. Allow strained syrup to cool completely to room temperature.
04 - In a large bowl, whisk together pink grapefruit juice, zest, cooled basil syrup, lemon juice if using, and sea salt until fully incorporated.
05 - Refrigerate base for at least 1 hour until thoroughly cold, ensuring optimal freezing results.
06 - Transfer chilled mixture to ice cream maker and churn for 20-25 minutes according to manufacturer instructions until mixture reaches thick, slushy consistency.
07 - Spoon sorbet into freezer-safe container. Cover tightly and freeze for minimum 3 hours or until firm enough to scoop.
08 - Let sorbet stand at room temperature for 5 minutes before scooping. Garnish with fresh basil if desired.