Sambar is one of the mostly used dish in South India, especially Tamil Nadu. Onion sambar can be prepared when you are short of vegetables to make sambar.
 

Ingredients:   Small Onions - 20 (peeled) Tomato (medium sized) - 2 Green Chillies - 8 to 10 Toor Dal 1/2 Cup Sambhar powder -2 spoons Red chillie powder - 1 spoon Tamarind Extract - 2-3 spoons Turmeric a pinch Curry leaves and coriander 3-4 spoons of Oil Salt to taste For seasoning: Mustard Seeds - 1/2 spoon Urad Dal - 1 spoon Bengal Gram Dal - 1 spoon 4-5 Dry Red Chillies

Method:

Pressure cook dal with enough water and set aside.

Heat oil in pan. Add seasonings, fry for a while.

Add turmeric and sambar powder and red chilly powder (adding all the 3 powders at this time gives a nice red color to the sambar).

Then add peeled small onions, cut green chillies, curry leaves, diced tomatoes and tamarind pulp and 1/2 cup water. Allow to boil till onions are cooked.

Smash the cooked dal. Add to this boiling sambhar. Add enough water to bring it to sambhar consistency.

Allow to boil till, you get the aroma. Remove from flame.

Add chopped corriander on top. Can also add 1/2 spoon (not more than that) of Gingely oil, this gives additional taste.

Goes excellent with Idlis, Dosas, Uppumas and Plain Rice.