01 - Preheat the oven to 425°F and line a large baking sheet with parchment paper.
02 - In a large bowl, combine harissa paste, olive oil, smoked paprika, cumin, salt, black pepper, and minced garlic; stir until thoroughly blended.
03 - Add chicken thighs to the marinade and toss to coat evenly. Let marinate for at least 10 minutes or refrigerate up to 2 hours for enhanced flavor.
04 - Place sweet potato cubes and red onion wedges on the prepared baking sheet; drizzle with olive oil and season lightly with salt and pepper. Toss to coat and spread into an even layer.
05 - Arrange marinated chicken thighs on top of the vegetables in a single layer.
06 - Roast in the preheated oven for 40 to 45 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are tender and caramelized.
07 - Transfer to serving plates, garnish with chopped cilantro or parsley, and serve with lemon wedges.