Cut eggplants into thirds length-wise and then chop. Keep them in salted water to prevent them from discoloring.
Heat oil in a medium pan or a deep frying pan. Fry onion till light golden brown.
Add cumin seeds and cook for a minute till they splutter, and they release their aroma.
Add the tomatoes, and cook for a minute or so. Add the rest of the spices (salt, red chili powder, turmeric) and saute for about 30 - 45 seconds.
Cook on low heat till tomatoes soften (10-15 minutes). Add chopped potatoes and eggplants. Cover pot and keep on low simmer (dam) for 10-15 minutes. Make sure that the potatoes and eggplant are tender.
Add green chili’s and cook for 30-45 seconds. Take off the heat, garnish with coriander and serve with roti or rice.
Based on personal preference the eggplants can also be peeled. That will result in a lighter color of the final dish.