Directly roast the eggplants on the flame until completely charred from all sides.
This needs to be monitored to ensure that eggplants are rotated over to all sides and get uniformly charred. A knife can be passed through the eggplant at the end of 7-8 minutes, to check if it is cooked inside. In this case, knife will pass through smoothly, in case eggplant is uncooked inside, you will feel the resistance.
Remove the eggplants onto a plate and cover with a large bowl and keep aside.
In 5 minutes, the eggplant will be cool enough to handle, and you can peel off the skins by merely tugging at them. Mash all the flesh, discard the stems and keep aside.
In a heavy bottomed kadai, heat the oil.
Add the asafoetida, cumin seeds. Once cumin seeds splutter, add the ginger and garlic and saute for 30 seconds.
Add the finely chopped onions, toss well, sprinkle a pinch of salt. Cover and cook until onions are soft, around 5-7 minutes. Add the tomatoes with the remaining salt, and dry spices, cover and cook until tomatoes are completely soft and mushy. Stir this well.
To this, add the mashed eggplant flesh, around 1/2 cup water and bring to a simmer.
Sprinkle garam masala powder at this stage and simmer for 2 minutes. Remove from flame.
Garnish with fresh coriander and serve hot with chapatis.