In a medium saucepan, combine quinoa and water. Bring to a boil, then reduce heat and simmer for 15 minutes, or until all water is absorbed. Fluff with a fork and let cool.

While quinoa is cooking, chop cucumber, tomatoes, and red onion.

In a small bowl, whisk together olive oil, lemon juice, oregano, garlic powder, salt, and pepper.

In a large bowl, combine cooked quinoa, cucumber, tomatoes, red onion, feta cheese (optional), and Kalamata olives.

Pour dressing over the salad and toss gently to combine. Serve immediately or chill for later.