Place the eggplants in an oven safe dish large enough so it can hold the eggplants in a single layer. Sprinkle with some salt and half the turmeric. Drizzle 1 tsp of the oil, toss to coat and place in an oven at 400 degrees F for about 20-25 minutes until the eggplants are soft but not completely cooked.
Heat 1 tsp of oil in a saucepan. Add the cardamom, cloves, cinnamon, red chillies, coriander seeds, cumin seeds, fennel seeds and fenugreek seeds and toast until they start to get darker. Add the peanuts and toast until the peanuts start to get lightly golden. Remove to a plate.
Add the coconut to the skillet and toast, stirring constantly, for just a few seconds until the coconut starts to get lightly brown. Don't leave the coconut on the stove unattended because it will burn in an instant.
Place the toasted spices and peanuts, coconut, jaggery and the remaining turmeric in a blender. Add enough water and blend into a very smooth paste.
Heat the last 1 tsp of oil in the saucepan and add the mustard seeds. When they sputter, add the sliced onion. Saute until it starts to brown. Add the garlic and ginger and saute for another minute.
Add the ground spices and when they come to a boil, add the eggplants. Add more water if the sauce is too thick.
When the sauce boils, turn down the heat so it just simmers, slap on a lid and cook for about 10-15 minutes or until the eggplants are really tender.
Add salt to taste. Garnish with some fresh coriander.