Fry thinly slice onions until golden brown and keep aside in the pan that you intend to cook the roast.
On medium flame, Fry the potatoes and brinjal and keep aside separately.
On low flame, heat the sauce pan with the fried onions by tilting the sauce pan to one side.
Add 2 tbsp of the frying oil and cook the tomato paste until the raw smell disappears.
Next, add the turmeric powder, chili powder and salt to taste and cook the spices.
Combine the onions and the masala paste. Mix in the fried potatoes and pour in 3/4 cup water in 2 batches and mix thoroughly. The whole mixture will soften beautifully at this point
Towards the end add in the brinjal and mix slightly & check for salt. Switch off the flame and cover and keep for 10 mins
Garnish with coriander leaves (optional). Tasty Potato brinjal roast is ready to serve along with Chapati or Parotta.