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 one-inch cubes and chop the broccoli, bell pepper, and zucchini into 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 until well combined.
Place the chicken and all the vegetables onto the prepared baking sheet in a single layer.
Drizzle the lemon-herb marinade over the chicken and vegetables, then toss thoroughly with your hands or tongs to ensure everything is evenly coated.
Spread the mixture out again to ensure nothing is overcrowded, which helps the vegetables roast rather than steam.
Roast in the center of the oven for 18 to 22 minutes, or until the chicken is opaque and cooked through and the vegetables are tender with slightly browned edges.
Remove from the oven and let rest for two minutes before serving to allow the juices to redistribute.