In a small saucepan, combine granulated sugar with water over medium heat. Stir continuously until the sugar dissolves completely, about 2-3 minutes. Remove from heat and cool.

Chill a can of full-fat coconut milk overnight. Open the can and scoop out the thick coconut cream.

In a blender, combine coconut cream, cooled lemon syrup, fresh lemon juice, lemon zest, and sea salt. Add vodka or rum if desired. Blend until smooth.

Taste and adjust sweetness by adding more lemon syrup or sugar as needed.

Pour blended mixture into a freezer-safe container. Cover tightly and freeze for 4-6 hours or overnight.

Allow the mixture to soften for 5-10 minutes before serving. Scoop into glasses or blend again for a smoother consistency.

Garnish with lemon slices or toasted coconut flakes before serving.