Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and place them on one side of the prepared sheet pan.
Add the chopped zucchini, red bell pepper, and sliced red onion to the other side of the pan.
Drizzle the olive oil over the chicken and vegetables, then sprinkle with sea salt, black pepper, and garlic powder, tossing well to coat every piece.
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 pan is roasting, rinse the quinoa under cold water and place it in a small pot with the water; bring to a boil, then reduce heat, cover, and simmer for 12-15 minutes until the liquid is absorbed.
Fluff the cooked quinoa with a fork and transfer it to a large mixing bowl.
Add the roasted chicken, vegetables, lemon juice, lemon zest, and fresh parsley to the bowl with the quinoa.
Gently fold all the ingredients together until well combined and serve warm.