Soak tamarind in hot water for 30 mins. Extract juice, adjust water to make it to 1 cup total.
Cut brinjal to four in the bottom, only through ¾th, not fully. Leaving the stem intact.
In a pan, add 1 teaspoon oil, add peanut, red chilli, coriander and fenugreek seeds. Give it a roast.
Add curry leaves and roast until all the ingredients turn fragrant. Do it in low flame to ensure even cooking.
Cool down and grind it to powder with salt, jaggery and turmeric.
Stuff this powder into slit brinjal. There will be remaining powder. Set aside.
In a pan, heat oil, temper with mustard, curry leaves. Arrange the brinjal. Stir gently to coat oil everywhere.
Cook covered in low flame for 3 minutes. Turn in between each minute to ensure even cooking.
Add 1 cup water and the tamarind extract. Cook covered for 5 minutes.
Add the remaining spice powder and cook for 3 more minutes or until the gravy thickens. Oil will separate and look shiny.