Sambar onions (tiny purple shallots that you get in India) are absolutely perfect for this sambar because they are small enough to go in whole. The shallots I get here are enormous in comparison, and I usually have to chop them in half when I make this sambar. Ordinary onions can be used too, and with great results.
But - and I speak for myself - it is the sambar onions that make this dish what it is... and they also bring back memories of those "special" days when my mother would make arachuvitta sambar paired with hot roasted baby potatoes and plain white rice. She didnt make it as often as she was asked, because peeling those pesky little onions was a finicky, annoying, time-consuming job that left you with smelly fingers for ages. Despite that, it was a job I took on gladly. The end result was so worth it!
I dont have any photos for this (bar the masala ingredients) because my camera battery gave up just then. But since no camera can capture the aroma of this sambar, which is its real essence, I guess it doesnt really matter.
This sambar can of course accommodate any combination of most vegetables, so you dont have to stick to just onions. I like to throw in a handful of frozen green peas once the other vegetables are cooked. Peas dont take long to cook at all, and if you drop them in with the other veg, they go grey and mushy by the end. If you add them towards the end of cooking, they stay fresh and green.
ADDENDUM: Omigosh, I have just been made to realise that I forgot one important ingredient in making this sambar - cooked tuvar dal - and my unreserved apologies for the omission! Thank you, kind reader, for pointing out the omission! (The recipe has been updated.)
Recipe for: Arachuvitta sambar (sambar with ground coconut masala)
1 cup cooked and mashed tuvar dal (split pigeon peas)
1 generous tsp tamarind paste dissolved in 4 cups water
2 medium onions, sliced thin (or 1 cup baby shallots, peeled)
2 tsp mustard seeds
6-7 curry leaves
1/4 tsp asafoetida powder (optional)
1 tsp oil
1 tbsp fresh chopped coriander leaves for garnish
For the ground coconut masala:
2 tsp chana dal
2 tsp whole coriander seeds
1/2 tsp black peppercorns
1/4 tsp cumin seeds
7-8 dried red chillies (or to taste)
3 tbsp freshly grated coconut
1. Dry-roast the coconut masala ingredients (bar the coconut itself) till the coriander seeds turn a darker shade.
2. Cool, then grind along with the grated coconut to a smooth, thick, pourable paste, using a little warm water (5-6 tbsp). Set aside.
3. In a pan, heat the oil and add the asafoetida powder if using, the mustard seeds and curry leaves. Close the pan until the mustard seeds finish popping.
4. Add the sliced onions/baby shallots to the pan and stir fry for two minutes, then add the tamarind water.
5. Bring it to a rolling boil on high, then turn down the heat to medium and let it bubble gently until the onions turn translucent (or the vegetables are cooked). (Add the frozen green peas now, if using).
6. Add the ground coconut masala and cooked tuvar dal, mix well. Add salt to taste. Let the mixture boil gently for 5 minutes. It should not be watery.
If the sambar seems too watery, remove some of the liquid from it (making sure to leave out the vegetables!) and dissolve some rice flour or corn flour. Add it back to the sambar and let it bubble for a couple more minutes.
7. Garnish with chopped fresh coriander leaves and serve hot over plain rice, with any vegetable dish.