Boil the dal, mango, green chilies and turmeric powder with 1 1/2 cups water for 4-5 whistles. Mash well and keep aside.
Heat oil in a pan and temper with red chilies, mustard seeds, urad dal and chana dal. Saute for a few seconds.
Add the onion, garlic and curry leaves. Stir fry till light brown. Add the coriander powder and red chili powder. Give it a stir.
Now add the boiled dal and salt to taste. Simmer for 2-3 minutes and switch off the flame. Garnish with coriander leaves and serve with hot steamed rice.