In a blender, blend the Meyer lemon juice and cucumber together, creating cucumber water. Strain the liquid through a fine mesh strainer to remove any seeds.
Place 1/2 cup water into a saucepan and add the sugar and lavender. Bring the mixture to a simmer to dissolve the sugar and infuse the simple syrup with the lavender flavor. Then set aside to cool.
Once the syrup is cool, remove the lavender sprigs and mix the syrup into the cucumber water. Add in the Meyer lemon zest and then pour the mixture into a 9 by 13-inch glass baking dish. Place the dish into the freezer to chill. Every 30 minutes, scrape the mixture with a fork to break up the ice crystals and to keep it light and fluffy. Continue scraping every 30 minutes for at least 2 hours.
Scrape the granita into elegant glasses and sprinkle with fleur de sel.