Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Dice the chicken breast into bite-sized pieces and chop the bell pepper, zucchini, and red onion into uniform chunks.
Place the chicken and vegetables on the baking sheet, drizzle with olive oil, and sprinkle with garlic powder, sea salt, and black pepper.
Toss everything together until evenly coated, then spread in a single layer to ensure even roasting.
Roast for 18-20 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
In a large bowl, combine the roasted chicken and vegetable mixture with the cooked quinoa.
Add the lemon juice, lemon zest, and chopped fresh parsley, tossing well to incorporate the bright flavors before serving.