Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Pat the chicken breast dry with paper towels and cut it into 1-inch bite-sized cubes.
In a large mixing bowl, combine the cubed chicken, drained chickpeas, broccoli florets, and chopped red bell pepper.
Drizzle the olive oil over the mixture and sprinkle with sea salt, black pepper, and garlic powder, tossing thoroughly to ensure everything is evenly coated.
Spread the chicken and vegetable mixture in a single layer across the prepared baking sheet.
Roast in the oven for 18-20 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
While the tray is roasting, whisk together the lemon juice and tahini in a small bowl until smooth to create the dressing.
To assemble, place the cooked quinoa in the base of a bowl, top with the roasted chicken and vegetable mixture, and finish with the lemon-tahini drizzle.