Mamidikaya pappu or Raw Mango Dal is a special dish of andhra. As this is a seasonal dish, i suggest you to try it when sour mangoes are available. I have used only moong dal, but toor dal and moong dal in equal quantities can also be used.
In andhra many dishes are prepared raw mango, my personal favourite is this dal. A chutney can also be made by combining raw mango and fresh coconut. Soon that recipe would be available. Rasam, flavoured rice and many more are prepared with these mangoes. We can make it a bit spicy also as the tanginess dominates the dal generally. Always the consistency can be adjusted by adding some water if dal gets thicker in later time.