Cut brinjals into medium size and put it in water. Chop the onion finely.
Soak tamarind in water and squeeze out the juice by adding 3 cups of water little by little.
Pressure cook the thuvar dhal along with a pinch of turmeric powder till soft.
In a kadai put a teaspoon of oil and roast Bengal gram dhal, urad dhal, coriander seeds and red chillies separately. Add coconut gratings at the end and fry for a while. Remove and cool. Mix all the roasted ingredients and fried coconut grating and grind to a fine paste.
In a kadai put the oil and when it is hot add mustard. When it pops up, add fenugreek seeds, ground nut and fry just a second and add chopped onion, curry leaves and fry till the onion turns transparant. Then add turmeric power, sambar powder, salt and mix well. Now add tamarind water and stir it. Add brinjal pieces and allow to cook on medium flame till the brinjal is soft.
Then add the ground paste, cooked dhal and mix well. Let it boil for few more minutes.