Bring a medium pot of water to a boil and cook the orzo pasta according to the package instructions until it is tender.
Drain the canned tuna thoroughly and place it in a large bowl, using a fork to break it into small, flaky pieces.
Dice the cucumber and red onion, halve the cherry tomatoes, and slice the kalamata olives into small rounds.
In a small mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, sea salt, and black pepper.
Drain the cooked orzo and rinse it under cold water to cool it down before adding it to the bowl with the tuna.
Add the diced cucumber, onion, tomatoes, olives, and fresh parsley to the bowl and toss everything together.
Pour the lemon dressing over the salad and stir well to ensure every ingredient is coated in the bright flavors.
Top the salad with the crumbled feta cheese and serve immediately or store in the refrigerator for later.