Adapted from Smitten Kitchen
Makes enough to fill two glasses with ice cubes; we quadrupled it to fill a pitcher.
1/4 cup fresh-squeezed lemon juice
1/2 cup fresh watermelon puree, strained through a coarse strainer to remove seeds
3 tablespoons simple syrup*
3/4 cup (6 ounces) cold water
Stir it all together and serve over ice. Garnish it with a thin watermelon or lemon wedge, if you’re feeling fancy.
*How to make Simple Syrup: Simmer one part water with one part sugar (I did a cup of each and ended up with more than I needed for a quadruple batch) until sugar has dissolved. Let cool. Or, for a speedier method, simmer one part sugar with half as much water and once it has dissolved, add the second half of the water, cold, which cools the mixture down faster.