Soak the tamarind in about 2 cups of hot water and extract the juice.
Wash and cook the payatham paruppu / Moong dal with enough water and pinch of turmeric powder until soft. Keep it aside.
In a pan, heat the oil and add all the seasoning ingredients. Fry them until they are aromatic and golden brown.
Add the chopped onions and saute it for 2-3 minutes until slightly softened. Now add the tomatoes and fry for a minute.
Add the chopped eggplant and green chilies and saute for 5 minutes.
Now add the tamarind water to the vegetables and mix well. Add the Sambhar powder and salt and let the gothsu come to a boil.
Cook until the eggplant is soft and cooked.
Add the cooked payatham paruppu / moong dal and mix well. Add the jaggery as well and let the gothsu simmer for about 5 minutes.
Garnish with cilantro and serve hot with Pongal!