First make the spice mix for stuffing the eggplants. Heat the oil in a pan, and all the spices except the coconut. Roast over low heat until they give off an aroma (donu2019t let them burn). Transfer to the jar of your mixer/ grinder or spice grinder. In the same pan, toast the coconut until it turns golden brown. Add to the roasted spices and grind to a slightly coarse powder. Add a little salt to this, mix and keep aside.
Soak the tamarind in half a cup of warm water for about 15 to 20 minutes. Extract the pulp and keep aside, discarding the solids.
Now prepare the eggplant for stuffing. Make sure all your eggplant have their stalks intact. Wash and pat dry the eggplant. Then slit them lengthwise into 4 or 8 from the bottom to the stalk keeping them joined at the stalk so the pieces donu2019t separate completely.
Carefully stuff each eggplant with about a teaspoonful of the spice mixture, making sure it gets into all the crevices. Save the leftover spice mix.
Heat 2 to 3 tbsp of the oil in a frying pan, and place the stuffed eggplant gently in it. Turn the heat to low and let them cook well. Keep turning them gently so that they get cooked on all sides. Cook with the pan covered to ensure the eggplant gets cooked through. When theyu2019re done, remove them carefully from the oil and let them rest on a plate.
Add the remaining oil to the pa. When the oil is hot, add chillies, the garlic and the ginger. Sautxe9 a couple of times and then add the onions and curry leaves. Sautxe9 further until the onion turn soft and golden brown. Add the turmeric powder and the remaining spice mix to the pan, and let it cook till the oil surfaces.
Add the tamarind extract and the jaggery and more salt as required. Cook on medium heat for a few minutes until you have a thick-ish gravy like sauce. Gently place the eggplant in the pan, and let them simmer in the sauce over low heat for about 4 to 5 minutes.
Transfer to a serving dish and garnish with chopped coriander. Serve warm with chapathis or rice.