01 - Place the watermelon cubes in a blender and blend until completely smooth, creating a uniform liquid base.
02 - Pour the watermelon puree through a fine mesh sieve into a large pitcher to remove pulp and achieve a smoother consistency, if desired.
03 - Add the freshly squeezed lemon juice and sugar or agave syrup to the pitcher. Stir vigorously until the sweetener completely dissolves into the mixture.
04 - Pour in the cold water and mix thoroughly. Taste the lemonade and adjust sweetness or acidity levels according to personal preference.
05 - Refrigerate the lemonade for at least 1 hour to allow flavors to meld, or serve immediately over ice for a quick refreshment.
06 - Add fresh lemon slices and mint sprigs as garnish just before serving to enhance visual appeal and aromatic experience.