Boil the Toovar daal with Tomatoes, Turmeric powder, salt and water. Once its cooked, mash the daal and tomatoes properly.
Keep cooking and add the black pepper powder, Red chili powder, Rasam powder, ginger puree and coriander leaves. At this point, make sure you add more water if needed. Rasam is watery and not too thick.
For tempering, add Ghee to a pan. Add mustard seeds, curry leaves, asafoetida and dry red chilies. Once they splutter, add it to the Rasam. Serve hot with boiled rice.