Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch bite-sized pieces and chop the broccoli, bell pepper, and zucchini into similar sizes to ensure even cooking.
In a small glass bowl, whisk together the extra virgin olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Place the diced chicken and all the chopped vegetables onto the prepared sheet pan.
Drizzle the lemon-herb dressing over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure every piece is well-coated.
Spread the ingredients out into a single, even layer, making sure not to overcrowd the pan so the vegetables roast and brown rather than steam.
Bake for 18 to 22 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.