Recipe Chef John's Watermelon Agua Fresca

Scoop watermelon flesh into a blender, add 2 cups of cold water, and blend for one minute until smooth. Strain the liquid through a fine mesh sieve into a bowl to remove pulp and skim off any foam. Create a simple syrup by heating sugar and 1/2 cup water until dissolved, then cool and stir it into the watermelon juice. Pour the mixture into a 2-quart pitcher and refrigerate for 30 minutes or until cold. Serve the finished drink over ice in tall glasses with straws.