Wild Blueberry Lemon-Thyme Granita

In a medium sauce pan over medium-high heat, bring the water and sugar to a boil. Reduce the heat to simmer until the sugar has completely dissolved. Add the lemon juice, zest and thyme and let sit until completely cool, about 30 minutes.   Meanwhile, puree the blueberries using a blender. Once the lemon-thyme syrup has cooled, remove the thyme sprigs, and add to the blender and blend to combine.   Pour liquid into a shallow glass baking dish and place in the freezer. Every 45 minutes, stir the semi-frozen mixture with a fork until firm, about 4 hours. Before serving, scrape the surface with a fork until granular crystals form. Scoop and serve.