Apply little oil over the brinjals and roast it in a direct flame. [Hold the brinjal using a tong or insert a sharp rod (like “Vadai Kambi”) into the brinjal and rotate it over direct flame till it is fully roasted and becomes black]. The picture below shows the brinjal before and after roasting.
Remove the black skin from the brinjals and keep aside.
In a small kadai add a teaspoon of oil and fry asafotida for few seconds. Add urad dhal and fry till it become light brown. Add tamarind and fry that too for few seconds. Then add red chillies and fry for few more seconds, remove from the kadai and let it cool.
Grind all the above fried items along with salt to a coarse powder. Before removing add the roasted brinjal and grind it for one or two rounds.
Season it with mustard.
Goes well with Idli/Dosa/rice uppuma/salt kozhukattai.