Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Pat the chicken breast dry with paper towels and slice into 1-inch bite-sized pieces.
Chop the broccoli into small florets, the red bell pepper into 1-inch squares, and the zucchini into half-moons.
Mince the garlic cloves finely.
In a large mixing bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper.
Add the chicken and vegetables to the bowl and toss thoroughly until everything is evenly coated in the herb marinade.
Spread the mixture in a single layer on the prepared sheet pan, ensuring the pieces are not overcrowded so they roast rather than steam.
Bake for 18-22 minutes, or until the chicken is cooked through and the vegetables are tender and slightly charred.
Remove from the oven and serve immediately, perhaps with an extra squeeze of fresh lemon if desired.