Soak 2 tbsp chana dal and 1 tbsp rice for about half hour.
Grind the soaked dal and rice along with the coconut, curry leaves, coriander leaves and green chillies to a fine paste. Use green chilies as per your heat tolerance and how spicy the chillies are.
Mix this prepared paste into roughly 2 cups of thick sour yogurt. Whisk well to combine.
In a pan, combine 1/2 cup water with chopped spinach and boil for 4-5 minutes with constant mashing, until spinach is cooked thoroughly.
Add the yogurt with spice paste to the cooked spinach and salt as required. Cook this on a low flame. Once the curry starts simmering, remove from flame. Do not boil this on a high flame or the yogurt may split.
Prepare the tempering for the mor keerai. In a kadai or small pan, heat 2 tsp coconut oil and fry the mustard seeds and urad dal. Once the dal turns golden brown, stir in the asafoetida for a few seconds. Add curry leaves and stir for a few seconds. Transfer this over mor keerai and serve hot.