Ingredients 

1. Tomato - 1 (or use 1/2 tsp of tamarind paste).
2. Salt - as required
3. Rasam powder(chaaru podi) - 1/2 to 1 spoon
4. Green chillies - 1 or 2 (optional)
5. Pepper powder - pinch (optional)
6. Coriander leaves - few
7. Seasoning - 1 tsp of urad dal, mustard seeds, 1/2 tsp of jeera, pinch of hing and few curry leaves

Method: 

1. Put a vessel on the stove and add 1 spoon of oil and add the chopped tomato pieces (and green chillies if desired).
2. Fry for some time until tomato pieces become soft and like a paste.
3. Pour 2 cups of water add salt , rasam powder, pepper powder & coriander leaves and boil for 5 min.
4. Reduce the heat & let it boil for 10 more minutes.
5. Put a fry pan on stove add 2 spoons of oil, after heated add urad dal fry for a min and add red chilli piece, inguva, curry leaves ,mustard seeds, jeera and switch of the stove. Add this to the rasam.