Place the watermelon cubes and tomatillo slices in a large bowl.
In a small bowl, add the chopped mint and jalapeno. Squeeze the fresh lime juice on top, stir in the vinegar, sprinkle the salt and mix. Pour the olive oil and vegetable oil, and mix with a whisk or fork until well emulsified.
Pour the vinaigrette on top of the watermelon and tomatillos, toss well and sprinkle the cheese on top.