Making ground spice & herbs mixture

Cup of Yum
1. Take roughly chopped coriander stems with or without leaves (about a handful of coriander stems) in a blender or mixer jar. Also add the peeled garlic cloves and roughly chopped ginger. 
2. Add cumin seeds and black peppercorns. 
3. Grind to a coarse paste or a semi-fine paste. Remove in a separate bowl or plate.

Making tomato puree

1. In the same blender add the tomatoes (rinsed and chopped). 
2. Grind or blend to a smooth puree. If you want, you can blanch tomatoes and then puree them – for a bright red color in the rasam.

Making tomato rasam

1. In a heavy pan or pot, heat the oil. Keep the flame to its lowest.
2. Add the mustard seed and let them begin to crackle. 
3. When the mustard seeds start to crackle, then add urad dal.
4. Stirring often fry urad dal until they turn golden.
5. Now add the dry red chilies (halved and seeds removed) and 1 pinch asafoetida. In case the pan becomes hot, then switch off the heat.
6. Stir and fry for a few seconds till the red chilies change color.
7. Add the coarsely ground coriander stems+ginger+garlic mixture and curry leaves. If the pan becomes too hot, then you can turn off the heat.
8. Sauté for a minute on lowest heat taking care the mixture does not burn. You will get a nice aroma while sautéing this mixture.
9. Add turmeric powder and mix it with the rest of the mixture.
10. Now add the tomato puree and mix it very well. Take care as the mixture splutters when you add the tomato puree.
11. Sauté for a minute. Season with salt as per taste.
12. Then add 1.5 cups water. If you like a slightly thinner tomato rasam, then you can add some more water. But do not add too much water as the flavors get diluted.
13. Mix well and simmer Thakkali Rasam on medium-low heat until the rasam comes to a simmer.
14. Overall simmer for 9 to 10 minutes.
15. Finally turn off the heat and add the chopped coriander leaves. Check the taste of tomato rasam and add more salt if needed.

Serving suggestions

1. Serve tomato rasam hot, either like a curry over steamed white rice or enjoy as a bowl of hearty soup. Both ways are great with a side of pappadums or a simple toasted bread.

Storage

1. Refrigerate any leftovers for a day. Reheat the rasam in a small pot or pan until warm or hot.
2. If you plan to make ahead the rasam then do not add coriander leaves. After you reheat rasam, add the coriander leaves.