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 uniform 1-inch cubes and chop the broccoli, bell pepper, and zucchini into similar bite-sized pieces.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, dried oregano, sea salt, and black pepper.
Place the diced chicken and all the vegetables onto the prepared baking sheet in a single layer.
Drizzle the lemon-herb dressing over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure everything is well coated.
Spread the mixture out evenly across the pan so the ingredients roast rather than steam.
Roast in the center of the oven for 20 to 25 minutes, tossing the ingredients halfway through the cooking time.
Check that the chicken is cooked through and the vegetables are tender with slightly caramelized edges before removing from the oven.
Transfer to a plate and serve immediately, optionally garnished with fresh parsley or an extra squeeze of lemon.