Wash brinjals, make slits in it and fill some salt in it. Wash and peel the potatoes, make slits and add salt in it.
In a pan heat mustard oil, add potato and brinjal in it and give a good mix.
Cover and cook till the vegetables are soft and keep stirring in between. Once cooked transfer to a bowl to remove extra oil.
In the pan where you cooked vegetables add in green chilli and let it crisp. Now add in masala, stir and cook for 1 minute.
Add in onion and salt, cook till onion turns golden brown. Now add in turmeric powder, red chilli powder,coriander powder and give a good mix.
Add in tomato, water and mix it well. Cover and cook everything for 3-4 minutes or till tomatoes are soft.
After 5 minutes add in potatoes, brinjals and mix well and increase the flame to medium.
Cook the vegetables in gravy for 2-3 minutes. After 2-3 minutes add in water and mix.
Lower the flame, cover with a lid and put a heavy vessel on it. Fill the vessel with water.
Let it dum for 5 minutes. After 5 minutes check the gravy and add in garam masala.