Place 6 lemons in a container and cover with water.
Let soak for 24 hours.
Cut the lemons into quarters, leaving the base of the fruit intact.
Pack the lemons tightly in a canning jar.
Add ¼ cup of coarse salt.
Seal the jar and store it in a dark place for at least four weeks before using.
Using a knife, make 2–3 cuts in the skin of each chicken piece to help the marinade penetrate.
Marinate the chicken (at least 30 minutes) with the spices (cumin, ras el hanout, ginger, turmeric, saffron, coriander, salt and pepper) and 1 tablespoon of olive oil.
Tip: You can marinate the chicken for up to 12 hours in the refrigerator.
Add 1 tablespoon of olive oil to the tagine. Over medium heat, sauté the onion and garlic.
Add the marinated chicken and cook over medium heat for 15 minutes, stirring occasionally.
After 15 minutes, add the olives, preserved lemon, and water. Cover with the lid and cook on low heat for 45 minutes
Adjust salt and pepper to taste
Serve with homemade fries or couscous