Watermelon & Strawberry Granita

1/3 cup sugar
1/3 cup water
1 large sprig fresh mint
¼ medium watermelon, deseeded and chopped
2 cups strawberries, chopped
Juice of 2 limes
1/4 cup vodka (optional)

Place the sugar, water and mint into a pot, then stir over gentle heat until sugar dissolves.
Remove from the heat and leave to cool completely to room temperature.
Place the cooled syrup (discard the mint), watermelon and strawberries into a blender and blend until completely liquid.
Add the lime juice and vodka, if using, then give one final blend.
Pour mixture into a freezer-safe dish, then freeze for 4 hours or until completely frozen.
Once ready to serve, use a fork to scrape the surface and shave ice flakes, serve in glasses.