Pour 1 cup of boiling water over crushed mint leaves and 2 tablespoons of honey or sugar. Stir mixture until sweetener dissolves and allow to steep and cool for 15 minutes.
While the mixture is cooling, put watermelon and 3 cups of water into a blender. Blend until smooth and strain watermelon liquid into a pitcher. Discard the solid leftovers.
Now strain the mint and sugar water, and discard the mint leaves. Add into the watermelon juice and top up with water. Add lime juice to taste and stir.
Garnish with extra watermelon, mint and lime slices if desired.