firstly, dry roast 2 tbsp coriander seeds, 1 tbsp cumin, 1 tbsp pepper, 2 tbsp toor dal, 2 dried red chilli and few curry leaves.
roast until the spices turn aromatic without burning them.
blend to a fine powder and rasam powder is ready. you can prepare this in large batch and store in an airtight container.
to prepare rasam, in a large kadai heat 2 tbsp oil.
splutter, 1 tsp mustard, ½ tsp cumin, pinch hing and few curry leaves.
add 1 tomato, 1 chilli, 1 cup tamarind extract, ½ tsp turmeric, 1 tsp salt and ½ tsp jaggery.
mix well, cover and boil for 10 minutes or until everything is well cooked.
further add 1 cup toor dal, 4 cup water and mix well adjusting consistency as required.
once the water comes to a boil add 2 tbsp of prepared rasam powder. you can adjust the amount of rasam powder based on the spice level.
mix well making sure there are no lumps.
boil for 2 minutes or until the flavours are well absorbed. do not over boil, as the flavours will be lost.
finally, add 2 tbsp coriander and south indian rasam is ready. keep aside.