1. Rinse the quinoa under cold water.
2. In a saucepan, bring water to a boil. Add quinoa, reduce heat, cover, and simmer for 15 minutes.
3. Remove from heat and let it 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, red wine vinegar, oregano, salt, and black pepper.
6. Pour the dressing over the salad and toss to combine.
7. Serve immediately or refrigerate for later.