Pressure – cook the dal with 6 cups of water. After 3-4 whisltes, add tomatoes, garlic, lemon grass, and cook until tomatoes are completely mashed. Strain the rasam (juice). Add tamarind pulp, salt and black pepper.
Heat oil and fry mustard seeds, cumin seeds, asafetida, red chilies and curry leaves. Add the fried seasoning to the rasam and cook for a few minutes.