Preheat your oven to 400°F / 200°C. Pierce the eggplants all over with a fork, place them in a roasting pan, and roast for about 1 hour and 15 minutes, or until they have completely collapsed and the flesh is tender.
Once cool enough to handle, peel the skin away from the eggplants and finely chop or mash the flesh.
Set aside.
Heat the oil in a large nonstick wok, karhai, or frying pan over medium-high heat.
Once hot, add the cumin seeds and let them sizzle for 3-4 seconds.
Add the fennel and nigella seeds and cook for another 2 seconds until fragrant.
Add the chopped onions and sauté for 5-6 minutes, stirring frequently, until they soften and start to brown at the edges.
Stir in the ginger, garlic, and green chilies, and cook for 2 minutes until the raw smell disappears.
Add the chopped tomatoes and salt, and continue to cook for 5-6 minutes, until the tomatoes break down and the oil begins to separate from the mixture.
Add the mashed eggplant to the pan.
Stir everything together well and cook for 5 minutes, allowing the smoky eggplant to absorb all the flavors of the spiced tomato base.
Stir in the fresh cilantro, cook for a final 2-3 minutes, and serve hot.
After roasting, place the hot eggplants in a covered bowl for 10 minutes. The trapped steam will loosen the skins, making them incredibly easy to peel.