Cut watermelon into cubes, appropriately 1-2" wide.
Place watermelon, blackberries, cheese and mint in a large bowl and gently toss to combine.
Serve and top with additional cheese or mint as desired. Enjoy!
Notes
Can't find Cotija cheese? No big deal - just substitute feta cheese.Vegan? Leave out the cheese altogether and sprinkle the watermelon with 1 teaspoon salt instead.