1/2 cup caster sugar
6 cups diced seedless watermelon
juice of 1 lemon
Place sugar and 1 cup water into a small saucepan. Stir over a medium heat until sugar has dissolved. Bring to the boil and cook for 1 min. Remove from heat and let cool.
Place the watermelon, lemon juice, a pinch of salt and the sugar syrup into a blender or food processor and process until smooth. Strain mixture through a sieve. Transfer mixture to a 2L capacity shallow metal baking dish or mixing bowl and cover with plastic wrap. Freeze for 2-3hr or until edges begin to firm.
Stir the mixture thoroughly with a fork and return to freezer for a further 45 min. Repeat this process every 45 min for 3-4 hr or until firm. Store in an airtight container in the freezer. Scoop ice into bowls and serve.