Pat the chicken thighs dry with paper towels and season them with salt.
Heat the olive oil in a tagine or a large, heavy-bottomed pot over medium-high heat. Add the chicken thighs, skin-side down, and sear until golden brown, about 5 minutes per side. Remove the chicken and set aside.
In the same pot, reduce heat to medium and add the chopped onion. Sauté until translucent, about 5 minutes.
Add the minced garlic, ginger, cumin, cinnamon, turmeric, black pepper, and cayenne pepper. Cook, stirring constantly, for another 2 minutes until the spices are fragrant.
Pour in the chicken stock and bring to a simmer, scraping up any browned bits from the bottom of the pot.
Return the chicken to the pot, cover, and simmer for 30 minutes.
Add the preserved lemon rind and olives to the pot, cover, and continue to cook for another 15-20 minutes, or until the chicken is tender and cooked through.
Taste and adjust seasoning with salt if necessary.
Garnish with chopped cilantro just before serving.