Roast the onions on a dry cast-iron or non-stick skillet until they soften and brown spots appear. Remove to a blender.
Roast the coriander seeds, cumin seeds, sesame seeds, poppy seeds, fenugreek seeds and peanuts until they start to change color and smell fragrant, about a minute or two on medium heat. Add to the blender.
Now add the ginger, garlic, turmeric powder, red chilli powder, sugar, salt and coconut milk to the blender.
Blend until you have a fairly smooth paste.
Now stuff this paste into the prepared eggplants.
Heat the oil in a cast-iron or other skillet.
Add the curry leaves, stir for a minute, and then add the eggplants one by one, placing them away from you so the oil doesn't splatter on you.
Cook, stirring occasionally, for about 8-10 minutes or until the eggplants begin to soften.
Now add the remaining paste and ¾ cup of water.
Bring to a boil, turn the heat to medium-low, cover and cook, stirring occasionally, to ensure all sides of each eggplant get cooked.
The dish should be done when the eggplants are tender enough to be pierced through with a fork, and when specks of oil have risen to the surface.
Garnish with chopped cilantro.