Technique
Blend the watermelon completely, then pass it through a fine-mesh strainer without forcing thick pulp through. Mix in the lime, syrup, and water only after straining so you can taste the clean base and adjust it before serving.
A vibrant, hydrating Mexican-inspired non-alcoholic drink made with fresh watermelon, lime, and a touch of mint. Perfect for summer.

TonicDB editorial guide
Watermelon supplies both flavor and most of the liquid in this agua fresca, while lime keeps the ripe fruit from tasting flat. A small amount of syrup rounds out a less-sweet melon, and the added water keeps the result light enough to drink by the glass.
Blend the watermelon completely, then pass it through a fine-mesh strainer without forcing thick pulp through. Mix in the lime, syrup, and water only after straining so you can taste the clean base and adjust it before serving.
Serve very cold over ice with mint near the rim for aroma. This quantity makes several pours, so keep the extra refrigerated and stir it before refilling glasses because fresh watermelon juice separates as it rests.
Watermelons vary greatly in sweetness and water content. Adding all the syrup before tasting can make a ripe melon cloying, while pressing too much pulp through the strainer gives the drink a heavy, foamy texture.
For a livelier version, replace the two ounces of still water with sparkling water in each glass just before serving. Add it after the watermelon mixture is poured so the blender and stirring do not knock out the bubbles.
These notes explain how to execute and adapt the recipe shown above. Ingredients and serving traditions vary, so taste and adjust thoughtfully.
Contributed by @alfg