Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
In a small bowl, whisk together the harissa paste, half of the olive oil, honey, lemon juice, minced garlic, sea salt, and black pepper to create the marinade.
Place the chicken breast on one side of the prepared baking sheet and brush it generously on all sides with the harissa mixture.
In a separate bowl, toss the cauliflower florets, sliced zucchini, and chopped red bell pepper with the remaining olive oil and smoked paprika until evenly coated.
Spread the vegetables in a single layer on the empty side of the baking sheet, ensuring they are not overcrowded to allow for proper browning.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with charred edges.
Remove from the oven and let the chicken rest for 5 minutes before slicing it into strips and serving alongside the roasted vegetables.