Put all of the herb dressing ingredients into a blender and puree until smooth.
In a large bowl add the chopped kale and massage the leaves with the salad dressing until slightly softened (this helps reduce the bitterness of the kale).
Toss in the watermelon, mint, and cashews.
Combine until dressing is evenly distributed.
Keep leftovers in an airtight container in the fridge for up to three days.