In a medium saucepan, bring water to a boil. Add quinoa, reduce heat, cover, and simmer for 15 minutes or until the water is absorbed.
Let the quinoa cool to room temperature.
In a large bowl, combine the cooked quinoa, parsley, mint, tomatoes, cucumber, and red onion.
In a small bowl, whisk together the olive oil, lemon juice, salt, and pepper.
Pour the dressing over the quinoa mixture and toss to combine.
Serve chilled or at room temperature.