Tagine of chicken simply means a stew cooked in a special kind of pot with Mediterranean spices and preserved lemons. You don't need the pot, a casserole dish will do, but you do need the preserved lemons.
The recipe is not difficult and is really just home cooking Moroccan style. While using a tagine (a cooking pot with a conical lid) makes it more authentic, it's by no means essential. The dish works very well cooked on top of the stove in a saucepan, if that's all you have.
Preserved lemons can be bought in the better delis these days, and you can also make your own. In the absence of either you could use fresh lemon juice and the pared skin cut into strips, but it's nowhere near as good.
Moroccan cooks would use a whole chicken for this recipe, cut into individual joints. You can do the same, of course, but I've simplified that a little by using chicken thigh joints instead.
For 4, you need:
8 chicken thigh joints, skinned but bone in
1/4 cup cold stock or water
1 onion, chopped
2 crushed cloves of garlic
1/2 tbs paprika
1/2 tbs cumin
pinch saffron (optional)
2 tbs chopped coriander (cilantro) leaves
2 tbs chopped flat-leaf parsley leaves
2 tbs olive oil
1 tbs ghee (clarified butter)
1 preserved lemon, chopped
2 potatoes, cut into wedges
2 tomatoes, skinned, deseeded and chopped
salt and pepper to taste
Mix the stock, onion, garlic, paprika, cumin, saffron, coriander, parsley, salt and pepper in a food-safe plastic bag. Add the chicken pieces and leave to marinate in the fridge for at least three hours and preferably overnight.
Drain the chicken and discard the marinade.
In a heavy bottomed pot, saute the chicken in the oil and butter until browned. Add the potatoes, preserved lemon, tomatoes and enough water or stock to just cover the chicken. Gently simmer with the lid on for a further 30 minutes, remove the meat and vegetables and rapidly reduce the cooking juices by half.
Arrange the meat and vegetables on a warm serving dish and spoon the sauce over them. Garnish with fresh coriander, olives and fresh lemon wedges. Serve with rice or couscous and a green vegetable such as spinach.