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