1. Rinse the quinoa under cold water.
2. In a saucepan, combine quinoa and water. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes or until water is absorbed.
3. Remove from heat and let sit, covered, for 5 minutes. Fluff with a fork.
4. In a large mixing bowl, combine cooked quinoa, cherry tomatoes, cucumber, red onion, olives, and feta cheese.
5. In a small bowl, whisk together olive oil, lemon juice, oregano, salt, and pepper.
6. Pour the dressing over the quinoa mixture and toss to combine.
7. Serve immediately or refrigerate for later.