01 - Combine granulated sugar and water in a small saucepan. Bring to a simmer over medium heat, stirring until sugar is fully dissolved. Remove saucepan from heat, add fresh basil leaves, and steep for 10 minutes. Strain syrup to remove basil and discard the leaves.
02 - Place blueberries, lemon zest, freshly squeezed lemon juice, strained basil syrup, and a pinch of salt into a blender. Process until the mixture is completely smooth.
03 - For a silkier texture, pour blended mixture through a fine mesh sieve into a bowl to remove skins and seeds.
04 - Transfer mixture to a shallow freezer-safe container. Cover and freeze for 4 to 6 hours, stirring vigorously with a fork every 30 to 60 minutes to break up ice crystals until texture becomes smooth and scoopable.
05 - For an ultra-creamy texture, churn mixture in an ice cream maker following the manufacturer's instructions.