Wash the matar dal.
Boil the dal with turmeric, green chilli and 1 ½ cups water for one high, two low whistles.
Wash and slice the green mango. Slit the green chilli.
Open the cooker, add cut mango slices and green chilli and cook for 1 whistle.
Cool and whisk the Aam Dal.
Heat oil in a pan. Temper with mustard seeds and dry red chilli. Pour the the kancha aam er dal into the kadai and stir well. Add salt and sugar. Add water if the Kacha Aam Dal is too thick. Let the green mango dal simmer for 1-2 minutes. Remove Mango Dal into a serving dish.
Serve this sweet and sour Kancha Aamer Dal with steamed rice and alur choka.