Soak tamarind in warm water . Extract its pulp.Add some water ( say 3-4 cup) to the extracted tamarind pulp such that the water is tangy but not too tangy.
Add some jaggery and salt to the tamarind water and keep to boil.
Meanwhile dry roast jeera n pepper in a kadai.
Fine Powder them in a mixer
When the water is about to boil, add roasted pepper – jeera powder and mix well.Once it starts boiling, keep the flame on low and let it simmer for about 5-10 minutes.Taste test .If required add some more salt and jaggery .
Heat a tsp of ghee, add mustard seeds and garlic pieces.When mustard splutters and garlic turns light brown , add curry leaves and switch off. Pour it over the rasam.garnish with coriander leaves if you want.
Serve piping hot rasam with hot steaming rice or sip it as a soup or as a yummy tonic for your cold and cough.
If you want you can do roasted pepper jeera powder in large quantity and store in an airtight container. No need to refrigerate.
Instead of tamarind you can use kokum.
If you want you can add little urad dal too along with jeera and pepper while roasting.