Start once the cooker is ready to be opened.
Extract the juice of the tamarind by squeezing it in the water in which it is soaked. Strain the tamarind extract into a bowl, checking that there are no pieces of tamarind pulp or seeds, and pour into a pan and heat on the stove.Add another ¼ cup of water to the tamarind pulp and squeeze out any remaining juice. Add to the pan on the stove. Discard the used tamarind pulp.
To the tamarind extract on the stove, add chopped tomatoes, rasam powder, cumin powder, pepper powder, asafoetida powder, a few minced curry leaves and salt.
Bring the rasam to a boil and then reduce the stove to low flame. Let the rasam simmer for 5 minutes on low heat so that the raw taste of the chili in the rasam powder disappears. By now the aroma would be wafting all around your kitchen!
Mash the cooked thowar dal in its own liquid so that the grains combine.
Pour the dal into the rasam along with ¼ cup of water. Bring to a boil, keeping it boiling for 2 minutes. Simmer on low flame for 3 minutes. Taste for correctness of salt.Add the chopped coriander and remove from the stove.
Keeping the stove on low flame, heat ghee in a small tempering pan, add mustard seeds and let them burst. Add cumin seeds and after 10 secs, switch off the stove, quickly adding the chopped curry leaves. I love the crackle and aroma of fresh curry leaves in hot ghee!
Pour the ghee tempering on the rasam and keep the pan covered.
Serve hot with rice and ghee, a sauteed curry and papad.