Cut rigan (brinjal) and potatoes into medium thick slices.
Now in a pan, add coriander seeds, cumin seeds, peanuts, fennel seeds, and black pepper. Saute on medium flame till it is slightly golden brown and aromatic. Switch off the gas and cool down the roasted masala.
Then add masala into the mixture jar and grind it into a coarse powder. Keep it aside.
Now in a pan, add some oil and fry rigan and potato chips till it becomes slightly soft and cooked 80%. Take it out into a plate.
Then in the same pan, add 3 tbsp oil, cumin seeds, hing, curry leaves, green chili paste, and ginger paste. Saute it.
Now lower the flame, and add turmeric powder, red chili powder, coriander powder, and garam masala. Saute it.
Then add fried rigan and batata slices. Mix well.
Now add grinded masala, salt, and jaggery. Mix well.
Cover and cook sabzi on low flame, so masala absorbs in it.
Now switch off the gas, and add lemon juice and coriander leaves. Mix well.
Rigan batata nu shak is ready. Serve with roti and raita.