Carefully slice each avocado in half and remove the pit. Gently scoop a little bit of the flesh out of the center to create more space for the filling. Reserve the scooped avocado for later.
In a mixing bowl, combine the cherry tomatoes, cucumber, red onion, Kalamata olives, feta cheese, and parsley.
In a small bowl, whisk together the olive oil, lemon juice, salt, and pepper. Pour this dressing over the vegetable and feta mixture, and toss gently to combine.
Add the reserved avocado flesh (chopped) to the salad mixture and gently fold to combine without mashing the avocado.
Spoon the Greek salad mixture into the hollowed out avocado halves, packing it in nicely.
Optional: Drizzle a little more olive oil on top and sprinkle with extra feta before serving.
Notes
Serve on a colorful plate, garnished with parsley and olives.