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 bite-sized cubes and place them on one side of the prepared sheet pan.
Add the broccoli florets, sliced bell peppers, and sliced zucchini to the other side of the pan.
Drizzle the olive oil over both the chicken and the vegetables, then sprinkle evenly with sea salt, black pepper, garlic powder, and dried oregano.
Toss the chicken and vegetables separately on the pan to ensure they are well-coated with oil and spices, then spread them out into a single layer.
Roast in the oven for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly caramelized edges.
While the sheet pan is in the oven, ensure your quinoa is cooked and kept warm.
To assemble, place the fluffy cooked quinoa in the bottom of a bowl and top with the roasted chicken and vegetable mixture.
Finish the dish with a fresh squeeze of lemon juice over the top to brighten all the flavors before serving.