In a large bowl, combine the cooked quinoa, chickpeas, cherry tomatoes, cucumber, baby spinach, and red onion. Toss gently to mix the ingredients evenly.
In a small bowl, whisk together the tahini, lemon juice, olive oil, minced garlic, salt, and pepper until smooth. If the dressing is too thick, add a tablespoon of water to reach your desired consistency.
Drizzle the tahini dressing over the grain bowl mixture and toss gently to coat all the ingredients.
Serve immediately, garnished with fresh parsley, or refrigerate for 30 minutes to allow the flavors to meld before serving.