In a pan add 3 tsp oil and add the mustard seeds, urad dal, red chili and chana dal.
Once the dal turns golden brown, add 1 cup sliced onions. Use small onions for making this gotsu.
Add little salt and cook the onions till translucent.
Now add 1 cup of thin tamarind extract, I soaked a small gooseberry sized tamarind in water and extracted the juice.
Add the turmeric powder, sambar powder, salt and asafoetida to this.
Mix well and boil this for 5 minutes.
Now add the cooked moong dal to this.
Add 1 cup of water to adjust the consistency.
Mix well and boil this for 3 minutes.
Add few curry leaves.
Switch off the flame.
Onion gotsu is ready to serve.
Serve with Idli, dosai or Venpongal too.