In a pot heat oil and add the cumin seeds. When cumin seeds become lightly brown add the chopped garlic, ginger root and whole green chili and stir for a minute. Add in the chopped onions and fry onions until they are golden brown. Remove the green chilli and set aside.
Now add the chopped tomatoes and fry until the oil starts to separate and the tomatoes are soft. Then add in the turmeric powder and fry for a minute. Then add in the red chilli powder, coriander powder and cumin powder and mix for a minute. Add in the potato pieces and fry for 5 minutes. Then add the brinjal (eggplant) pieces and fry for another 5 minutes.
Now add in 2 cups of water. When water comes to a boil, stir, lower heat to low, cover and let cook.
When the eggplant and potatoes are well done, garnish with coriander leaves, mix and turn off stove.