Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Cut the chicken breast into 1-inch bite-sized cubes and place them in a large mixing bowl.
Chop the broccoli into small florets, seed and dice the red bell pepper, and slice the zucchini into half-moons.
Mince the garlic cloves finely and add them to a small bowl with the olive oil, dried oregano, sea salt, and black pepper.
Whisk the oil and spice mixture together, then pour it over the chicken and vegetables in the large bowl.
Toss everything thoroughly until the chicken and produce are evenly coated in the garlic herb oil.
Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded so it roasts rather than steams.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Remove from the oven and immediately drizzle with fresh lemon juice to brighten the flavors before serving.