Start by preparing the watermelon and cucumber. Dice the watermelon into bite-sized pieces and the cucumber into half-moon shapes. Place them in a large mixing bowl.
Add the thinly sliced red onion and crumbled feta cheese to the bowl with watermelon and cucumber.
In a small bowl, whisk together the extra virgin olive oil, balsamic vinegar, salt, and black pepper until well combined.
Drizzle the dressing over the salad mixture and gently toss everything together to combine, ensuring not to break the feta too much.
Finally, sprinkle the chopped mint leaves over the salad and give it a gentle toss again to distribute the mint throughout.
Allow the salad to sit for about 10 minutes to let the flavors meld together before serving.
Notes
Let the salad sit for a few minutes to enhance the flavors.