Wash the dal well with water a few times. Cook the dal with the water and turmeric powder in a sauce pan or in a pressure cooker.
Once done, add salt, mix well and keep on low heat.
Grind the ingredients under "to grind to a paste" to a very fine paste, adding a little water if needed (as little as a tbsp or two)
Add this to the dal mix, increase the heat to medium high and let it cook for a few minutes until the dal and the ground paste is mixed well.
Now heat the coconut oil for the seasoning and add the mustard seeds to it. Once they splutter, add the onions. Once the onions turn light brown and a little crispy, add the curry leaves and the chilli. Pour this onto the dal mixture and mix well.
Serve with rice, rotis or just as it is as a soup.