Pressure cook dal and crush garlic, cumin and peppercorns and keep them both ready.
Mix in Stock, tomatoes, green chilli, red chilli, curry leaves, turmeric powder, Tamarind extract and let it boil in medium flame for 10 min.
When it has reduced a little and tomatoes are softened, Add crushed garlic, cumin seeds and peppercorns. Mix well and let it boil for 2 more minutes
Add cooked and mashed dal, salt, asafoetida and let it just come to boil, Do not let it boil at this stage. When it becomes frothy. switch off stove.
Heat ghee in tadka, crackle mustard seeds, cumin seeds, fenugreek and curry leaves. Add this to the rasam. Sprinkle chopped coriander leaves.