Mix the lentils and turmeric, add water and cook until the lentils are really soft and mashable. Pressure-cooking works best here -- and the fastest-- but you can do this on the stovetop. Use enough water to cover the lentils by an inch, bring to a boil, lower heat to a simmer, cover the pot and cook the lentils until they are soft and mushy. You will need to check frequently to ensure the water hasn't dried out.
Make the ground masala. Heat 1 tsp of oil and add the masala ingredients. On medium heat, saute the ingredients, stirring frequently, until the coconut turns a few shades darker. Be watchful because coconut burns easily.
Remove the masala ingredients to a blender, add enough water to make a paste, and blend to a smooth paste. Set aside.
In a large saucepan, place the chopped eggplant, add the tamarind, some salt, and enough water to almost cover the vegetables. Bring the mixture to a boil, turn heat to low, cover and cook until the brinjals are thoroughly cooked. Don't take shortcuts here because half-cooked brinjal is worse than no brinjal at all.
Add the cooked lentils, peanuts, and ground masala paste. Stir well, add water if the mixture is too thick, bring to a boil, lower heat, and cook at a gentle simmer for about 10 minutes.
In a small saucepan, add the remaining 1 tsp of oil and then add mustard seeds. When the mustard sputters, add the coconut and curry leaves.
Saute the coconut and curry leaves until the coconut turns lightly golden.
Add to the lentils and mix thoroughly. Stir in the coriander leaves.
Serve hot with some boiled rice and potato curry.