Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and chop the broccoli, bell pepper, and zucchini into uniform chunks to ensure even cooking.
In a large mixing bowl, combine the chicken and vegetables with the extra virgin olive oil, garlic powder, dried oregano, sea salt, and black pepper, tossing until everything is thoroughly coated.
Spread the mixture in a single, even layer on the prepared baking sheet, making sure not to overcrowd the pan so the vegetables roast rather than steam.
Roast in the oven for 18-22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.
While the tray is roasting, rinse the quinoa under cold water and cook it in a small saucepan with 0.5 cup of water until the liquid is absorbed and the grains are fluffy.
Assemble your bowl by placing the fluffy quinoa at the base and topping it with the roasted chicken and vegetable mixture.
Drizzle with fresh lemon juice just before serving for a bright, zesty finish that ties all the flavors together.