Heat the oil in a nonstick pan. Add mustard seeds, chopped onion and grated ginger.
Frying onion and ginger
Cook till golden brown. Add chopped green chillies, eggplant pieces, salt and turmeric powder. Cook for 4-5 minutes.
Added green chillies and eggplant
Add red chilli powder. Cook it covered till soft.
Added spices
Add tamarind paste and mash the eggplants a little.
Added tamarind and water
In a separate pan, prepare the tempering. Heat a tbsp of oil, add cumin seeds, whole red chilli and kari patta. Fry for a few seconds till cumin seeds puff up and red chillies are fried. Turn off the heat.
Preparing tempering
Add the tempering to the cooked eggplant.
Added tempering to eggplant
Mix everything and serve it hot with Roti or Parantha.
Notes
I did not mash the eggplants but they taste even better when mashed up a little.
I used the long eggplants but you can use any kind. Ultimately they are going to be a little mashed up.