Wash and cook the tur dal in a pressure cooker upto 2 whistles and switch off the flame. Allow the pressure to release by itself.
Meanwhile heat oil in a deep pan, add garlic, onion, add tomatoes, turmeric, red chilli powder and green chillies.
Cook all the ingredients for 2 minutes, then reduce to low heat, and let it simmer, stirring at regular intervals.
Now add the mashed tur dal, Sambar masala and let it simmer.
To prepare the tempering, heat ghee in frying pan, add mustard and cumin seeds, stir on medium heat until they splutter, add garlic and stir -fry until golden brown.
Then add red chillies and curry leaves and sauté for a minute.
Now pour the tempering over the simmering dal.
Remove and serve hot with rice.