This easy frozen cocktail recipe is summer party ready! Non-alcoholic variation in the recipe notes.
Mix frozen watermelon cubes, rum, lime juice, orange juice, and simple syrup in a blender until smooth. (Stop to scrape the sides occasionally if not using a high speed blender.) Blend in additional simple syrup to taste. Serve immediately, garnished with a wedge of lime.
*To make simple syrup, combine equal parts water and granulated sugar in a saucepan. (1 cup water to 1 cup sugar). Heat, stirring, until sugar is dissolved and small bubbles begin to form around the side of the pan. Remove from heat and let cool to room temperature. Store in an airtight container in the refrigerator for 3-4 weeks.
Omit rum and increase orange juice to 1/2 cup, adding a bit of water to the blender to thin the mixture, as needed.