Pressure cook the toor dal along with the peanuts(you dont have to soak either of these beforehand) with a pinch of turmeric powder and salt.
Let the steam release. Meanwhile dry roast all the ingredients for the paste in a pan over medium heat. Let cool and grind into a paste.
To the dal and peanut mixture, add the sliced onion and the tomatillo along with the spice paste. Rinse the blender jar and add the water to the dal mixture.
Add the turmeric powder and salt. Cover and let it come to a boil. Cook until the tomatillo and onion turn soft and the kuzhambu comes together.