01 - Combine water and sugar in a small saucepan. Bring to a gentle simmer over medium heat, stirring constantly until sugar completely dissolves. Remove from heat immediately.
02 - Add fresh basil leaves to the hot syrup, pressing gently with a spoon to release essential oils. Cover and steep for 10 minutes to extract aromatic flavors.
03 - Pour the syrup through a fine mesh strainer into a clean mixing bowl, pressing to extract all liquid. Discard the steeped basil leaves.
04 - Whisk the freshly squeezed pink grapefruit juice, grated zest, and optional lemon juice into the basil-infused syrup until fully incorporated.
05 - Cover the bowl and refrigerate for at least 1 hour until the mixture reaches 40°F throughout, ensuring proper churning texture.
06 - Transfer the chilled base to an ice cream maker and churn according to manufacturer instructions, typically 20–25 minutes, until achieving soft-serve consistency.
07 - Move the churned sorbet to a freezer-safe container, seal tightly, and freeze for minimum 3 hours until firm enough to scoop.
08 - Let the sorbet rest at room temperature for 5 minutes before scooping to achieve ideal texture. Serve immediately in chilled bowls.