1. In a large frying pan, heat 1 tablespoon of the oil and saute the chicken in two batches until brown on both sides. Set aside.
2. Heat a 6- to 8-quart casserole and add the remaining 3 tablespoons of oil. Add the garlic, onion, ginger, turmeric, paprika, salt and pepper and cook for about 5 minutes until the onion is softened.
3. Add the chicken, tomatoes, parsley, coriander, and lemon and bring to a simmer. Cover and simmer over low heat for about 30 minutes, or until the chicken is cooked. Add the olives and cook for 5 minutes longer. Salt to taste.
