First heat ½ tsp of oil in a pan, add the onion, garlic and saute until translucent. Transfer to a plate.

 

Now, add the tomato to the same pan and saute until it is slightly wilted. Transfer to the plate with onion.

 

Now, add dry red chillis to the same pan and saute for 30 secs and then transfer to the plate. Let the onion, tomato and chillis come to room temperature.

 

Add everything to a mixie, along with salt, tamarind, water and grind to a smooth paste.

 

Again heat the pan with ½ tsp oil, add the mustard and once it splutters, add the remaining ingredients listed under "To temper" in the given order. Once the broken urad dal starts to become golden brown, add the ground paste to the pan and saute until it reaches desired consistency and the raw smell of onions are completely gone.

 

 

Serve as a side with idli, dosa or kara kuzhi paniyaram.