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 1-inch cubes and chop the broccoli, bell peppers, and zucchini into similar sizes to ensure even cooking.
In a large mixing bowl, whisk together the olive oil, lemon juice, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken and vegetables to the bowl, tossing thoroughly until every piece is well-coated with the herb marinade.
Spread the mixture in a single layer on the prepared baking sheet, making sure not to overcrowd the pan so the veggies roast rather than steam.
Bake for 18-22 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with slightly charred edges.
Garnish with fresh chopped parsley and an extra squeeze of lemon before serving warm.