Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Chop the red bell pepper, red onion, and zucchini into uniform bite-sized pieces.
Slice the chicken breast into even strips to ensure they cook at the same rate as the vegetables.
In a large mixing bowl, whisk together the harissa paste, extra virgin olive oil, sea salt, and black pepper.
Add the chicken strips and chopped vegetables to the bowl, tossing thoroughly until every piece is coated in the spicy marinade.
Spread the mixture in a single, even layer onto the prepared baking sheet.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables have developed charred, caramelized edges.
Remove from the oven, drizzle with fresh lemon juice, and garnish with chopped parsley before serving hot serving.