Dice cucumber, cherry tomatoes, bell peppers, and red onions. Chop parsley and mint.
In a saucepan, bring vegetable broth or water to a boil. Add quinoa, reduce heat to low, cover, and simmer for 10-15 minutes or until all the liquid is absorbed. Fluff the quinoa with a fork and let it cool.
In a bowl, combine cooled quinoa with diced cucumber, cherry tomatoes, bell peppers, red onion, parsley, and mint.
To create the dressing, whisk together the olive oil, lemon juice, salt, and pepper in a small bowl.
Drizzle the dressing over the quinoa and vegetables. Toss gently. Serve chilled or at room temperature.