Pat the chicken thighs dry with paper towels and trim off any excess fat or skin if needed. Drying them first really helps the marinade stick.
In a large bowl, combine the harissa paste, salt, pepper, cumin, ground coriander, smoked paprika, olive oil, lemon juice, and minced garlic. Give it a good stir to bring it all together.
Add the chicken thighs to the bowl and toss well so every piece is fully coated. Cover and let it marinate for at least 30 minutes. If you have a couple of hours, even better.
Arrange the chicken thighs in a single layer in the basket. Air fry at 400°F (200°C) for 10 minutes. Check that the chicken is cooked through (internal temperature should reach 165°F / 74°C). If it needs a little more time, air fry for another 2 to 3 minutes.
Let the chicken rest for a few minutes before slicing. This keeps all those juices locked in. Slice it up and use it in wraps, bowls, or serve it whole alongside rice and salads.