Begin by cutting the cucumbers lengthwise into quarters as described above.
Once the seeds are smashed out, cut the cucumber slices into roughly one inch pieces, place in a serving blow and season with a large pinch of salt. Allow the cucumbers to rest for five to ten minutes so the salt can draw out the excess moisture.
Next, take a cup or more of cubed watermelon and cut it into matchsticks. Set aside until ready to assemble the salad.
For the vinaigrette, combine ½ c to 1 cup of cubed watermelon, a tablespoon of olive oil, a teaspoon of mirin or white wine vinegar, and one one jalapeño, seeds removed, into a food processor or blender until well blended.
Pour off any excess liquid from the cucumbers and add in matchstick cut watermelon. Pour vinaigrette over the salad and toss gently. Top with lime zest, mint and some fresh lime juice. Let sit in the fridge for 30 minutes before serving.