Place the sugar and water in a small saucepan over low heat and stir until dissolved. Add the berries and simmer for 3–4 minutes. Cool slightly and pour into a 27cm x 18cm metal tin. Freeze for 4–5 hours, breaking up with a fork after 2 hours and just before serving.** Serves 6.
* It’s important to freeze the granita in a metal tray because the metal keeps the mixture colder and at the right consistency.
** Breaking up the granita at intervals during the freezing time separates the ice crystals before they are fully set.