In a small saucepan, bring water to a boil. Add quinoa and give it a quick stir. Cover the saucepan, reduce heat to low and simmer for 15-16 minutes, or until the quinoa is tender and the water has been absorbed. Remove from heat and let stand 5 minutes. Then fluff with a fork. Allow it to cool to room temperature.
Meanwhile, in a small bowl, whisk together the garlic, olive oil, lemon juice, pepper and salt. Set the dressing aside.
In a large bowl, combine grape tomatoes, carrots, scallions and spinach. Stir in quinoa. Pour the dressing over the quinoa mixture and toss. Taste and adjust seasonings. Serve at room temperature.