Steps
In a big pan, take 1 litre of water + lemon-sized lump of tamarind + 2 tablespoons of coriander seeds + 2 dry red chillies + salt. Boil till water reduces to half the original volume.
Then filter the rasam (to remove the tamarind and corriander seeds).
In a small pan, take few curry leaves + 2 dry red chillies + 1 teaspoon cummin seeds + 2 crushed garlic pods.
Once it starts sputtering, add this mixture to the rasam.