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 a paper towel and cut into bite-sized 1-inch cubes to ensure even cooking.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Place the chicken cubes, broccoli florets, and sliced zucchini on the prepared sheet pan.
Drizzle the lemon-herb mixture over the chicken and vegetables, tossing thoroughly with your hands or tongs to coat every piece.
Spread everything out in a single layer, ensuring the pan isn't overcrowded so the vegetables 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, optionally garnishing with extra fresh herbs.