Wash and Soak Chana Dal overnight.
Next day strain the water. Add 4-5 glasses of water and boil the Chana Dal till it is cooked through.

Strain the water. Reserve this water for making Aamati (curry).
Take a thick bottom vessel or kadhai. Add jaggery and the boiled dal. Mix continuously so that dal doesn't stick to the bottom.
Now using a hand blender, blend the dal jaggery mixture to get a smooth and fine puran.

Switch off the gas flame. Once it is completely cooled, Add all the spice powders and keep aside.

Now take a large bowl. Add dry flour, salt and Turmeric to it. Heat 3 Tablespoon of oil in a pan. Once cooled slightly, but warm, add to the flour and mix well. Add water a little at a time and knead a soft dough. Add 2-3 tablespoon more oil and keep kneading the dough. Cover and keep aside for 10 minutes.

Now take a lemon size dough ball. Shape it into a bowl. Add puran (double the size of the dough ball).close the edges and start rolling like a paratha. Use dry flour in between if required.
Flatten from all sides.
Heat a tawa and cook the puran poli from both the sides. Apply some oil while cooking.
This will help to keep the polis soft for a longer time.