Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into bite-sized cubes and chop the broccoli, bell pepper, and zucchini into uniform pieces.
In a small bowl, whisk together the olive oil, lemon juice, garlic powder, dried oregano, sea salt, and black pepper.
Place the chicken and vegetables on the prepared sheet pan and pour the lemon-herb marinade over them, tossing well to coat every piece.
Spread the mixture in a single layer, ensuring nothing is overcrowded to allow for even roasting and browning.
Roast for 20-25 minutes, or until the chicken is cooked through and the vegetables are tender with slightly charred edges.
Remove from the oven and serve immediately, perhaps with an extra squeeze of fresh lemon for brightness.