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 water is absorbed.
3. Remove from heat and let it sit, covered, for 5 minutes. Fluff with a fork and let it cool.
4. In a large mixing bowl, combine the cooled quinoa, cucumber, red bell pepper, red onion, parsley, and feta cheese.
5. In a small bowl, whisk together the olive oil, lemon juice, salt, and black pepper. Pour over the salad and toss to combine.
6. Serve immediately or refrigerate for later.