Make the yellow watermelon juice in a Vitamix blender: add about 4 cups cubed watermelon and process on variable speed, slowly increasing from lowest setting to 4 and blending for less than a minute so that flesh is puréed and seeds remain whole. Strain juice into a glass measuring cup and reserve 2 cups for recipe; use the remaining for another purpose.

1½ cups yellow watermelon juice is the minimum for this recipe.

Combine yellow watermelon juice, St. Germain liquor, lime juice, double simple syrup, and enough water to bring total liquid to 3 cups. Pour into an 8-by-8-inch glass dish and freeze. Scrape the granita with a fork every hour until slightly slushy and completely flaked, about 4 hours for this blend. Enjoy!

Granita keeps surprisingly well in the freezer—for days and days, making it an ideal make in advance refresher.