• 8 cups chopped seedless watermelon (about 6 pounds)
• 1/2 cup freshly squeezed lime juice (about 4 limes)
• 2 to 4 tablespoons sugar
• 1/2 cup vodka (optional)
• Ice cubes, for serving
• Fresh mint leaves, for serving

Working in batches, puree watermelon in a blender with lime juice until smooth. Add 2 tablespoons sugar, and blend to combine. Taste, adding more sugar if necessary. Transfer to a pitcher. Stir in vodka, if using. Cover, and chill for up to 2 hours. Before serving, stir well, and serve over ice, garnished with mint.