In a blender, add the watermelon cubes, fresh lemon juice, honey or agave syrup (if using), and mint leaves.
Blend until smooth.
Taste and adjust sweetness as needed by adding more honey or syrup.
Add a pinch of coarse salt after blending, to enhance the sweetness and bring out the flavor, ensuring that it doesn't dissolve too much during blending.
Pour the drink into glasses over crushed ice to ensure the drink stays chilled without diluting too quickly.
Garnish with additional fresh mint leaves or a small watermelon wedge.
Serve immediately and enjoy!