In a mixing bowl, combine the harissa paste, olive oil, smoked paprika, ground cumin, garlic powder, salt, and pepper. Mix thoroughly until it forms a marinade.
Add the chicken thighs to the bowl, ensuring they are well coated with the marinade. Cover and let them marinate in the refrigerator for at least 1 hour (or up to overnight for deeper flavor).
Preheat your oven to 425°F (220°C).
Place the marinated chicken thighs skin-side up in a baking dish. Squeeze the lemon juice over the thighs for added brightness.
Roast in the preheated oven for 30-35 minutes or until the chicken skin is golden brown and crispy, and the internal temperature reaches 165°F (75°C).
Remove from the oven and let the chicken rest for about 5 minutes before serving.
Garnish the chicken with freshly chopped cilantro or parsley, and serve with lemon wedges on the side.
Notes
For a milder flavor, adjust the amount of harissa paste used.