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 cubes and chop the zucchini, red onion, and bell pepper into similar bite-sized pieces.
In a large mixing bowl, whisk together the extra virgin olive oil, fresh lemon juice, dried oregano, minced garlic, sea salt, and black pepper.
Add the chicken, zucchini, onion, bell pepper, and whole cherry tomatoes to the bowl, tossing thoroughly to ensure every piece is coated in the herb marinade.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, ensuring they aren't overcrowded so they roast rather than steam.
Bake for 20 to 25 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred, caramelized edges.
Remove from the oven and let the pan rest for 3 minutes before serving to keep the chicken juicy.