Preheat your oven to 400 degrees Fahrenheit and line a large rimmed baking sheet with unbleached parchment paper.
Place the cubed chicken breast, broccoli florets, and cubed sweet potato on the sheet, then drizzle with olive oil and sprinkle with sea salt, black pepper, and garlic powder.
Toss everything thoroughly with your hands to ensure an even coating of oil and spices, then spread into a single layer.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165 degrees and the vegetables are fork-tender.
While the bowl components roast, whisk the tahini, lemon juice, and water in a small glass jar until the consistency is smooth and creamy.
Build your bowl by layering the cooked quinoa at the bottom, followed by the roasted chicken and vegetables, then finish with a generous drizzle of the tahini dressing.