In a pan, heat one tsp of oil. When the oil is hot, add the chopped onion.
Saute until it is soft. Transfer it to a plate.
In the same pan, add the dried red chilies, coriander seeds, and poppy seeds. Roast it over medium-low heat for about a minute. Do not let the poppy seeds brown up.
Now add the coconut and mix it well and turn off the heat.
Allow it to cool and grind into a paste by adding 1/4 cup of water.
Preparing the Vathal Kuzhambu:
In a wide pan or kadai, heat the oil. When the oil is hot, add the mustard seeds, fenugreek seeds, urad dal, chana dal, curry leaves, and asafoetida. Add the dried black nightshade berries and fry them until it turns brown. By the time the mustard seeds will start to sputter as well.
Now add the remaining half of the chopped onion and veggies if using. Saute until the onion turns translucent.
Next, add the tomatoes, salt, ground turmeric, and red chili powder if using.
Mix well and cover and cook and until the tomatoes turn soft and mushy.
Add the tamarind paste and one cup of water. Mix well and simmer until the raw smell of the tamarind goes off. If you are using veggies, cook until the vegetables are soft and tender.
At this stage, add the ground paste and rinse the mixer-jar with half a cup of water and add it to the kuzhambu.
Let it simmer for 5 to 7 minutes. By this time, the kuzhambu will come to a boil. Once the kuzhambu starts boiling, turn off the heat.
That's it. Yummy kuzhambu is ready. Serve it hot with rice and dry curries or kootu.
If you are using drumstick, add it after the onion turns translucent, add the drumstick, and half a cup of water. Let the drumstick soften a bit. You can also microwave the drumstick for 5 to 7 minutes and add it to the kuzhambu. But I would recommend simmering it along with onion as it adds a nice flavor.
Check the consistency of the kuzhambu towards the end and adjust the water accordingly. If the kuzhambu is thick, then add 1/2 more cup of water and simmer for 2 to 3 minutes. If kuzhambu is thin in consistency, then mix 1/2 tsp of rice flour with 2 tbsp of water and add it to the kuzhambu. Bring it to a boil and turn off the heat. Kuzhambu thickens as it cools down. Don't add extra rice flour.
As always, adjust salt and spice according to your preference. The same goes for tamarind also. I have explained about tamarind in my vathal kuzhambu post. The tamarind you use plays a significant role. The age of the tamarind determines the tanginess and the color of the kuzhambu. So adjust the tamarind according to the variety you have.
You can use veggies like brinjal, okra, drumstick for this kuzhambu. I have also included cooked cowpeas and black chickpeas in this kuzhambu.
Red chili powder is optional. You can even grind it along with the spice mix. Instead of red chili powder, you can add sambar powder too.