01 - Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper or aluminum foil for easy cleanup.
02 - In a large mixing bowl, combine the harissa paste, olive oil, smoked paprika, ground cumin, salt, black pepper, fresh lemon juice, and minced garlic. Stir to form a cohesive marinade.
03 - Add the chicken thighs to the bowl with the marinade. Toss thoroughly to ensure each piece is evenly coated. Allow to marinate for at least 15 minutes at room temperature, or refrigerate for up to 8 hours for a more intense flavor.
04 - Place the marinated chicken thighs onto the prepared baking sheet, ensuring the skin-side is facing upwards.
05 - Roast in the preheated oven for 30 to 35 minutes, or until the chicken skin is crisp and an internal thermometer registers 165°F (74°C) at the thickest part of the thigh, avoiding the bone.
06 - While the chicken is roasting, combine the Greek yogurt, ground cumin, fresh lemon juice, salt, and chopped cilantro or parsley in a small bowl. Mix well and refrigerate until ready to serve.
07 - Present the roasted chicken thighs hot. Drizzle each serving with a spoonful of the prepared cumin yogurt sauce. Garnish with lemon wedges and additional fresh herbs, if desired.