If using dry tamarind, soak it in ⅓ cup hot water and set aside. When it cools down, mash it with your fingers and keep ready.
Add dal to a cooker or pot. Rinse it well a few times. Pour 1½ cups water and pressure cook for 3 whistles. If using a instant pot, set the timer to 10 minutes with pressure cook setting. If using a regular pot, cook on a medium heat until dal is soft and mushy.
While the dal cooks, chop cabbage. Rinse it well and drain completely. Keep this aside.
Meanwhile in a small tadka pan, dry roast chana dal and red chilies until deep golden and aromatic.
Add cumin seeds and fry for 30 seconds. Turn off and cool. Later transfer to a grinder along with coconut. Pour little water and make a fine paste.
How to Make Cabbage Kootu
When the pressure releases, open the cooker and check if the lentils are cooked. They should be really soft and mushy.
Add chopped cabbage and turmeric. Stir and cook until the cabbage is soft and tender but not overcooked. (if using Instant pot, press the saute button)
Add the ground kootu paste and cook just for 2 mins. If the kootu turns thick, pour little hot water and bring to consistency. It should be ideally thick but of pouring consistency.
When the cabbage is cooked, add tamarind water or paste. I prefer to pass soaked tamarind through the strainer. Taste test and add more salt or tamarind if needed.
Heat ghee or oil in the same tadka pan for tempering.
Add mustard seeds, red chilli and curry leaves. When they begin to splutter, add hing.
Switch off and pour this to the cabbage kootu. Give a good mix and serve with rice or roti.