Grind all the ingredients for masala into a fine paste. Mix this with 2 cups of water and allow it to boil. Add the yogurt, turmeric, and salt, and cook for another 2 minutes. This is the mor-kozhambu.
Cook the toor dal in a pressure cooker. Add the spinach to the cooked dal and cook for 5 minutes. Add this to the mor-kozhambu.
In a pan, heat about 2 tablespoons of oil. Add mustard. After the mustard seeds pop, add the seasoning to the mor-kozhambu.