Rinse and soak the chickpeas for 6 to 8 hours in 3 cups of water for 6 to 8 hrs.
Drain the water after 6 to 8 hrs. Add 2 to 2.5 cups of fresh water and pressure cook the chickpeas for three whistles. If you use an Instant Pot, you can cook the chickpeas for 25 minutes at high pressure and release the pressure naturally.
Drain the water and set the cooked chickpeas aside.
Prepare the masala
Heat a pan or kadai and add 1 tsp of coconut oil.
When the coconut oil melts and becomes hot, add the coriander seeds, cumin seeds, whole peppercorns, cinnamon pieces, fennel seeds, cloves, cardamom, and dried red chilies—Roast over medium-low heat until the spices are fragrant and coriander seeds turn light brown.
Add the roasted gram and coconut and roast for a couple more minutes. Transfer this mixture to a mixer jar.
Heat 1 tsp of coconut oil in the same pan and add ½ of the chopped onion, garlic and ginger. Saute until the onion and garlic turn soft and the raw smell disappears.
Next, add the chopped tomatoes and saute till they turn soft. Transfer this to a mixer jar and allow the mixture to cool.
Add a handful of cooked chickpeas and turmeric powder to the mixer jar. Grind this into a smooth mixture by adding ½ cup of water or as needed.
Prepare the gravy
Heat a pan or kadai and add the remaining oil. When it is hot, add mustard, fennel, and curry leaves. Let the mustard seeds splutter. Then add the remaining onion (chop this batch finely) and saute until it is soft and translucent.
Now add the ground masala and one and a half cups of water. Mix well and ensure there aren't any lumps. Add the salt and bring this mixture to a gentle simmer.
When the mixture becomes frothy and gently simmers, add the cooked black chickpeas and mix well.
Bring the gravy to a gentle simmer, add cilantro, and mix. Turn off the heat and enjoy.
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Notes
We need one big onion for this recipe. And we use half for the masala paste and the other half for sauteing/gravy. You can chop half of the onion for the masala paste while the other half finely.
Adding cooked chickpeas while grinding the masala paste yields a thick gravy, which we prefer. I add roasted gram, too, which helps in thick gravy, but grinding black chickpeas adds flavor. You can skip roasted gram if adding chickpeas while grinding or vice versa, which is fine, too.
Traditional Kerala kadala curry calls for black/brown chickpeas, but you can swap it with other beans of your choice.
I have used both peppercorns and red chilies. Adjust them according to your taste preference. The same goes for salt, too.
You can skip coconut while preparing the masala and add coconut milk. Add coconut milk along with chickpeas directly to the gravy if you use coconut milk. Half a cup of thick coconut milk would be sufficient for this measure.