01 - Set the oven to 425°F and line a large baking sheet with parchment paper.
02 - In a large bowl, thoroughly mix harissa paste, olive oil, smoked paprika, cumin, salt, black pepper, and minced garlic.
03 - Add chicken thighs to the marinade and toss to coat evenly. Let rest 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 baking sheet. Drizzle lightly with olive oil, season with salt and pepper, then toss to coat and spread evenly.
05 - Layer the marinated chicken thighs atop the vegetables in a single layer.
06 - Bake in the preheated oven for 40 to 45 minutes until chicken reaches an internal temperature of 165°F and sweet potatoes are tender and caramelized.
07 - Transfer to serving plates, sprinkle with chopped cilantro or parsley, and accompany with lemon wedges.