Rinse the quinoa under cold water.
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.
Remove from heat and let it sit, covered, for 5 minutes. Fluff with a fork.
In a large mixing bowl, combine the cooked quinoa, cherry tomatoes, cucumber, red onion, and parsley.
In a small bowl, whisk together the olive oil, lemon juice, salt, and black pepper.
Pour the dressing over the salad and toss to combine. Serve chilled or at room temperature.