1. Pre-heat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
2. Slice the chicken breast into 1-inch bite-sized cubes and place them in a large mixing bowl.
3. Chop the red bell pepper, zucchini, and red onion into uniform pieces similar in size to the chicken.
4. In a small jar, whisk together the harissa paste, extra virgin olive oil, lemon juice, minced garlic, sea salt, and black pepper.
5. Pour the spicy marinade over the chicken and vegetables, tossing thoroughly until every piece is evenly coated.
6. Spread the mixture in a single layer on the prepared baking sheet, ensuring nothing is overcrowded.
7. Roast for 20 to 25 minutes, or until the chicken is cooked through and the vegetables have developed a beautiful charred edge.
8. Remove from the oven and let rest for 2 minutes before serving hot.