Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Cut the chicken breast into uniform 1-inch cubes to ensure even cooking.
Chop the broccoli, red bell pepper, and zucchini into bite-sized pieces.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken and vegetables in a large mixing bowl, pour the lemon-herb marinade over them, and toss until everything is thoroughly coated.
Spread the chicken and vegetable mixture in a single layer on the prepared baking sheet, ensuring they aren't overcrowded.
Bake for 18 to 22 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender-crisp.
Serve the roasted chicken and vegetables over the warm cooked quinoa for a complete, balanced meal.