Heat some oil in a large pan over medium heat.
Once oil is warm, add mustard seeds, coriander seeds, and cumin seeds if you have them.
Then add onions and green chili. Saute them stirring occasionally until they turn golden.
While the onions fry, rinse and cube brinjals. The author of this recipe recommends removing seeds from eggplants to avoid bitterness but I just kept them in. There weren't too many!
Keep them immersed in a bowl of water with ¼ tsp salt. This prevents discoloring & avoids bitter taste in the eggplants.
Then add tomatoes and salt. Fry for 2 mins. Cook covered until the tomatoes turn soft & mushy.
Then add red chilli powder, turmeric and garam masala. Saute until the masala turns fragrant.
Pour half cup water. Cover and cook till the brinjals turns soft and tender. If you prefer a dry curry then reduce the water.
Simmer till the brinjal curry becomes thick & slightly mushy. Taste test and add moresalt, red chilli powder or garam masala if needed. I strongly recommend simmering for a good long time at this point - if you think it's done but the eggplant still have any kind of shape, simmer for longer!
Add thick coconut milk in a volume that seems good to you and simmer for a minute.
When the curry begins to bubble, turn off the heat and sprinkle coriander leaves.
Serve brinjal curry with rice, roti or any flatbreads.