Kuzhambu means a thick mix/slurry. True to its name, this kuzhambu is a spicy thick gravy with a tamarind base, with a few vegetables, and dal. The difference between vathal kuzhambu, kara kuzhambu and this is that this has cooked dal added to it. Then why is it not sambar? Good question. We use a pre-made spice powder to season this dish, whereas for sambar, we freshly roast and grind spices to make the masala. Also, this is a bit thicker than sambar.
So, as far as tamarind based gravies go, there are mainly 3 kinds in Tamil (brahmin) cooking:
Vatha kuzhambu/kara kuzhambu: no dal, limited vegetables, more oil and almost like a pickle
Sambar: Tamarind, dal, vegetables, freshly roasted and ground masala
Kuzhambu: Thick tamarind gravy, premade masala/spice powder, dal, limited vegetables.
Try to use sesame oil for the tempering, the flavor is out of this world.
Any bland juicy vegetables would work for kuzhambu type gravies. My favorites are carrot, green pepper, yellow pumpkin, broccoli stem, chow chow (chayote squash)!
This kuzhambu reminds me of my patti (my mom's mother). My earliest memory of this kuzhambu is eating it at her house, what we called perambur patti house (Perambur in Chennai where they lived, as opposed to Purasawalkam patti, where my dad's parents lived). This kuzhambu, followed by thick fresh curd, slightly reddish from the clay pot in which it was set is a nostalgic meal I try to recreate, minus the clay pot yogurt, when I'm struck by pangs of nostalgia and craving comfort food.