To begin making the Thakkali Vengaya Sambar Recipe, wash toor dal and soak in water for 10 minutes. Transfer soaked toor dal to a pressure cooker, add 2 cups of water.

Pressure cook the dal for 3-4 whistles and let the pressure release naturally.

Open the lid, scoop out the cooked dal into a bowl. With the help of a potato masher mash the dal and keep aside. 

In a same pressure cooker, add the onions and tomatoes along with tamarind extract, sambar powder, salt and 1/4 cup of water. 

Close the lid and pressure for two whistles over the medium heat. 

After two whistles turn off the heat. Allow the steam to release naturally from the pressure cooker. Open the lid once the steam is released.

If you are not using the pressure cooker method - Heat oil in a saucepan, saute the smalls onions until tender and the sweet aroma is released.

Add the tomatoes, the sambar powder, tamarind extract and 1/4 cup of water and simmer until the tomatoes are tender for about 10 minutes. 

Now mix the cooked toor dal with the onion tamarind sambar curry. Stir to combine and transfer to a large saucepan.

Meanwhile, to temper the Tomato Onion Sambar, heat oil in a small pan, add mustard seeds.

Once mustard seeds start crackling add asafoetida powder, curry leaves and red chilli. Saute till the curry leaves turn crips. Turn off the heat and pour the seasoning into the sambar.

Place the Tomato Onion Sambar over medium-high heat and bring the sambar to a boil. Turn the heat to low and allow the sambar to simmer for about 5 minutes, stirring in between.

If the Tomato Onion Sambar is too thick, add a little water to get the right consistency and simmer. Taste the seasoning and adjust to suit your taste.

Garnish the Tomato Onion Sambar with chopped coriander leaves and serve hot. 

Serve Tomato Onion Sambar along with Beetroot Thoran and Steamed Rice for a weekday lunch or dinner.