Season the chicken breast with the sea salt, black pepper, and a pinch of the dried oregano.
Grill the chicken over medium-high heat for 6 to 7 minutes per side until fully cooked and juices run clear.
While the chicken rests, chop the cucumber into half-moons, halve the cherry tomatoes, and thinly slice the red onion.
In a small glass jar or bowl, whisk together the extra virgin olive oil, lemon juice, and the remaining dried oregano.
Slice the rested chicken breast into thin strips or bite-sized cubes.
In a large mixing bowl, combine the cucumber, tomatoes, red onion, olives, and sliced chicken.
Drizzle the lemon-oregano dressing over the salad and toss gently to coat all ingredients.
Transfer to a serving plate and finish by crumbling the feta cheese over the top.