01 - Combine sugar and water in a small saucepan. Bring to a gentle boil, stirring constantly until sugar completely dissolves. Remove from heat immediately.
02 - Add fresh basil leaves to the hot syrup. Cover saucepan with lid and let steep for 15 minutes to extract herbal flavors.
03 - Pour syrup through a fine mesh sieve to remove basil leaves. Discard used herbs. Allow syrup to cool completely to room temperature.
04 - In a large bowl, whisk together pink grapefruit juice, grapefruit zest, cooled basil syrup, lemon juice if using, and sea salt until fully incorporated.
05 - Refrigerate the mixture for at least 1 hour until thoroughly chilled. This step is essential for proper texture formation.
06 - Pour cold mixture into ice cream maker. Churn according to manufacturer instructions, typically 20-25 minutes, until mixture reaches thick, slushy consistency.
07 - Transfer sorbet to freezer-safe container. Cover tightly and freeze for minimum 3 hours until firm enough to scoop.
08 - Let sorbet stand at room temperature for 5 minutes before serving to soften slightly. Scoop into chilled bowls and garnish with fresh basil if desired.