1. Rinse quinoa under cold water.
2. In a pot, bring water to a boil. Add quinoa, reduce heat to low, cover, and simmer for 15 minutes.
3. Remove pot from heat and let quinoa sit for 5 minutes, then fluff with a fork.
4. In a large mixing bowl, combine cooked quinoa, cucumber, red bell pepper, and red onion.
5. In a small bowl, whisk together olive oil, lemon juice, salt, and black pepper.
6. Pour dressing over quinoa mixture and toss to combine.
7. Garnish with fresh parsley and serve.