Take a kadai add oil fry all the roast and grind ingredients till nicely done cool and grind to a powder and keep.2.Take a pan add half litre of water and let it boil.3.Now add chopped tomatoes to a mixer jar make puree add this to boiling water, then add slit green chillies and needed salt.4.Let it boil for for some three minutes.5.Then add the powder to it and let it boil for another two minutes.6.Make tadka in a pan with ghee make mustard to splutter with hing and curry leaves add this to boiling rasam and switch off.7.Add some chopped coriander and serve with white rice.
Notes
Tartness come only from the tomatoes so choose to add the tomatoes that a tart enough. I have not added turmeric powder if you need nice colour add one. Have to fry the rasam powder ingredients nicely golden so that we get nice porcha rasam.