In a small saucepan over medium heat, combine water, sugar and ginger slice. Cook and stir until sugar dissolved. Remove from heat and cool for about 45 minutes.

Peel the lychee and remove the pits. Save the juice in the process. Place the lychee flesh and juice in a blender or food processor. Blend until smooth. Add 1 tablespoon lemon juice and the cooled sugar syrup. Taste and add a little more lemon juice if needed.

Transfer the mixture to a flat-bottomed 9 x 13-inch baking or glass dish. Transfer to freezer and chill for 30 minutes.

Stir the mixture thoroughly with a fork and freeze again for 30 minutes. Continue to freeze for another 4 hours, scraping and breaking the mixture with a fork every 30 minutes. Scoop to serving cups and serve immediately.