Combine the water and sugar in a small saucepan over medium-high heat. Bring to a simmer and continue to heat until the sugar has dissolved. Remove from heat and allow to cool to room temperature. Set aside.
For the strawberry granita:
Using a blender, puree together the strawberries, lemon juice and water. Add the simple syrup and stir to combine. Taste and adjust by adding more simple syrup if necessary.
Pour the strawberry liquid mixture into a freezer safe pan and place into your freezer for about 30 minutes to 1 hour (depending on how cold your freezer is). Remove from the freezer and use a fork to stir up the icy liquid. Return to the freezer and remove every 30 minutes to scrape contents. It should take about 2 to 3 hours until the mixture has turned into ice crystals and looks like an icy slushy.
For the dessert:
Scoop out some vanilla ice cream and top with the strawberry granita and then sprinkle on some fresh blueberries. Add a mint leaf if desired and serve!