Preheat oven to 400°F (200°C).
Chop the chicken breast, broccoli, bell pepper, and red onion into bite-sized pieces.
Place the chicken and vegetables on a large sheet pan.
Drizzle with olive oil and sprinkle with sea salt, black pepper, garlic powder, and dried oregano.
Toss everything together until evenly coated, then spread in a single layer.
Roast for 18-20 minutes until the chicken is cooked through and the vegetables are tender and slightly charred.
While roasting, prepare the quinoa according to package instructions if not already cooked.
Assemble the bowl by placing the cooked quinoa at the base and topping it with the roasted chicken and vegetable mixture.
Finish with a squeeze of fresh lemon juice and a sprinkle of chopped parsley.