Soak toor dal in 3/4 cup of hot water for 30 minutes to 1 hour. Pressure cook the dal with a pinch of turmeric powder for 3 whistles. After the pressure release naturally mash the dal and keep it aside
In a cooking pan add ghee and chopped tomatoes and green chilli; saute in medium flame till tomatoes turn slightly mushy
Furthermore add rasam powder, turmeric powder, and salt; mix well and cook for 15 seconds
Add 2 cups + 1/2 of water, 1 + 1/2 teaspoon of tamarind paste, and cook on low flame for about 10 - 12 minutes or until the raw flavor of the tamarind goes off
Furthermore, add mashed dal to the rasam, chopped coriander, curry leaves, sugar, and a generous amount of hing, turn off the stove when you see frothy rasam
Finally, add ghee to a small tadka pan when it is hot add the ingredients under "to temper" and let it splutter. Add the tempering to rasam