Make a soft and sticky dough with plain flour, turmeric powder (if using) and 3/4 - 1 cup water. Pour sesame oil over the dough. Make sure the dough is completely covered in oil. Let it rest for half an hour -1 hour.
Soak chana dal overnight. Drain the water and rinse 2-3 times. Pressure cook chana dal with 5 cups water for 2 whistles on high flame (refer notes). Once the pressure drops naturally, open the cooker and drain the excess water.
Take a deep and wide pan and add cooked chana dal, sugar, crushed cardamom and 1/2 - 1 tbsp ghee. Cook till the mixture becomes thick, around 6-8 mins. You should be able to roll it into balls. If it's not thickening even after 8-10 mins, add 1-2 tbsp Besan (gram flour) and cook till the raw taste of besan goes. Let the mixture cool completely.
Make lemon size balls from the chana dal mixture. Divide the dough soaked in oil to equal size balls. The dough balls (plain flour) should be smaller in size than the chana balls.
Stretch the dough balls on your palm and make a thin layer. Place the chana dal ball in the middle and cover it with the stretched dough. Flatten the covered ball between your palms.
Coat the flattened disc in rice flour and roll it out as thin as possible. If it tends to stick, sprinkle some rice flour and continue rolling.
Heat a Tava and cook the boli on both sides, till the colour changes and brown specs appear. Make sure you dont overcook it. Drizzle some ghee on both sides while cooking.
Prepare the remaining dough in the same way.
Notes
I got around 20-25 small-medium size boli from the above qty. It is important that you should not over cook the dal. So keep a close watch while pressure cooking it. You can add turmeric powder to the maida (plain flour) or dal mixture to get a rich yellow colour. If the dal mixture tends to become dry while cooking, add a tbsp of ghee and mix well. Make sure the maida ball is stretched very thinly. If it's thick, boli will not be soft. Though sesame oil is traditionally used for soaking the dough, you can substitute it with sunflower oil. When you are rolling out the flour-dal mixture, make sure the edges are not thick, otherwise it become rubbery when it cools down. Store the boli at room temp in an airtight container for 2 days. Refrigerate for longer shelf life and microwave the boli for a few seconds before serving.