Soak 1 Tsp of tamarind in 1/2 cup water for 15-20 minutes . Extract the juice and set aside.
Whilst rinse and wash moong dal , add turmeric powder , oil and water .
Pressure cook for 3 whistles , allow pressure to settle down on its own . Open the lid and mash dal lightly.
Meanwhile dry roast all the chana dal , coriander seeds , red chillies and methi seeds till fragrant . Don't burn the spices.
In a small mixer jar , blend the dry roasted spices to fine powder.
Heat oil / ghee in a kadai ,add mustard seeds once it crackles , now add jeera seeds , curry leaves and hing.
Add chopped onion and green chillies , saute till onions turn translucent.
Now add in all chopped veggies , tomatoes , turmeric powder and cook for 3-4 minutes
Pour extracted tamarind juice and continue to cook for 2-3 minutes.
Add 1 cup water to the sambar powder , mix well and this into the vegetables.
Bring it to boil , now add cooked dal ,salt as required and mix well .
Add water as required , adjust the consistency , continue to cook for 5 more minutes and turn of the heat.
Garnish with coriander leaves and serve with Pongal , Idli or Sambar.