Pressure cook tur dal for 15 minutes till it's mushy.
In a mortar and pestle add peppercorns ,cumin seeds and dried chilli and crush coarsely. Atlast crush garlic.
In a bowl mash tomatoes and add coarsely ground powder.
To the tomato mixture at boiled Tur dal.Add tumeric powder and salt to taste.
For tempering add oil and ghee on a medium flame. To it add mustard seed , asafoetida and curry leaves.
Let the froth appears on top of the rasam mixture.Do not boil. Garnish with finely chopped coriander leaves.
Traditional tomato rasam is ready to drink as a soup or to mix and eat with plain rice.