Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and place them in a large mixing bowl.
Add the broccoli florets, chopped red bell pepper, and sliced zucchini to the bowl with the chicken.
Drizzle the olive oil over the mixture and sprinkle with the sea salt, black pepper, garlic powder, and dried oregano.
Toss everything thoroughly until the chicken and vegetables are evenly coated with the oil and seasonings.
Spread the mixture in a single layer on the prepared baking sheet, ensuring enough space for the vegetables to roast rather than steam.
Bake for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender and slightly browned.
Remove from the oven and serve the medley over the warm cooked quinoa, finishing with a bright squeeze of fresh lemon juice.