Heat 3/4 cm oil [less works well for me] in a frying pan over a medium-high flame. When hot, put in as many slices as the pan will hold in a single layer and fry them until they are a reddish-brown colour on both sides. On the pieces that have it, the skin side should be cooked very briefly as it tends to get tough. Remove the aubergine slices with a slotted spoon and keep on a plate lined with kitchen paper. Do all the aubergine slices this way. Turn off the heat. Remove most of the oil (save it for another dish). You will only need 3 tbs in the frying pan.
Put the fennel seeds in a coffee grinder reserved for spices and grind until you have a powder. Put this powder, as well as the ginger, whole black cumin, turmeric, and cayenne in a small cup.
Heat 3 tbs of oil in the frying pan over a medium flame. When hot, put in the asafetida. A second later, add all the spices in the cup plus 2 tbs of water. Stir for 20 seconds and then put in another 50 ml of water. Stir for another 10 seconds. Lower heat and add tamarind, salt, and another 250 ml of water [I use less]. Mix. Put in the slices of aubergine and bring to a simmer. Spoon the sauce over the aubergine slices, cover, lower heat, and simmer gently for 5 minutes.
Serves 4 [well, 3 more likely].