Heat 4 tablespoons of oil in a medium-sized, heavy-based saucepan and fry the onion until golden brown. Add the lamb, turmeric, salt and pepper and then the dried limes. Stir until the meat is well coated with the turmeric and sealed all over.
Add the canned chopped tomatoes, tomato purée/tomato paste and boiling water and half-cover the pan with a lid. Simmer on a low heat until the meat is tender enough to cut with a fork and the sauce has reduced to around 500 ml/just under 1 pint; this will take approximately 1–1½ hours.
While the meat is cooking, fry the aubergines until golden brown, preferably in a non-stick frying pan/skillet (if you use an ordinary frying pan, you may need more oil). Remove and pat dry on kitchen paper to remove excess oil. In the same pan, heat 1 tablespoon of oil and lightly fry the sliced tomatoes.
Return the aubergine slices to the frying pan/ skillet and turn off the heat. Pour half of the lemon juice and half of the liquid saffron over the aubergine and tomato slices. Set aside. When the meat is cooked, carefully arrange the aubergine and tomato slices in the sauce on top of the meat.
Reduce the heat to very low and let the mixture simmer very gently for about 15 minutes. (The aubergine and tomatoes will disintegrate if the sauce boils vigorously.)