Pressure cook moong dal nicely for 3-4 whistles adding a pinch of Haldi. Dal should be cooked completely.
In a large vessel add tomatoes, ginger, chilli, and turmeric.
Add around 3-4 cups water. Boil for 10 minutes or till tomatoes turns soft and mushy. If you want, can mash the tomatoes well using a laddle.
Next , add pressure cooked mashed moong dal.
Add salt, Curry leaves and chopped coriander leaves. Mix well.
Add some more water and adjust consistency as required.
Boil for 3-4 minutes on medium flame. Switch off .
Squeeze lime after switching off rasam .. else sometimes rasam might turn bitter .
Meanwhile, prepare the tempering by heating up ghee .Once the ghee is hot, add mustard seeds, cumin seeds . Once it splutters add red chilli, curry leaves, asafoetida and pepper.
Once the tempering splutters, pour the tempering onto prepared lemon rasam.
Serve lemon rasam/kat saaru / nimbehannu saaru hot with steamed rice. enjoy with a tsp of ghee drizzled on top and some papad / palya on the side .