Heat the oil in a large pan or tagine and brown the turkey pieces in batches on all sides. Remove from the pan and set aside.
Add the peppers and onion, sauté for 3 minutes, then stir in the ginger, garlic and jalapeno chilli. Cook for 3 minutes, add the tomatoes and cook for another 3 minutes. Stir in the turmeric, cumin, salt, pepper and chicken stock, bring to the boil and simmer for 10 minutes over medium-low heat.
Return the turkey to the pan with the lemon slices, black olives and coriander. Cover and simmer over medium-low heat for 15 minutes or until the turkey is cooked through. Serve over hot couscous.