Use a sharp knife to cut the watermelon into 1-inch cubes, removing any seeds if present, and place in a large blender.
4 cups ripe watermelon flesh, cubed
Add a splash of lemon juice and a handful of fresh mint leaves to the blender for extra flavor, if desired.
1 images lemon juice, a handful fresh mint leaves fresh mint leaves
Blend the mixture on high speed until completely smooth and the watermelon is liquefied, about 30-45 seconds. The color should be vibrant pink and the texture homogeneous.
4 cups ripe watermelon flesh, cubed, 1 images lemon juice, a handful fresh mint leaves fresh mint leaves
Place a fine mesh strainer over a large pitcher or bowl and pour the blended mixture through it, using a spatula or spoon to press the liquid through and leave pulp behind.
Discard the pulp and transfer the strained juice into glasses, optionally garnishing with a sprig of mint or a thin wedge of lemon for presentation.
Serve immediately over ice or chilled.