Soak channa dal in water for half hour.
Dry roast rice flour for 1 or 2 minutes on low flame.
Transfer to a mixing bowl.
In the same pan dry roast urad dal over low flame till golden brown in color and you can get the aroma.
Let it cool down completely.
In a mixie jar, take the roasted urad dal and pottukadalai (roasted gram dal) and grind to a fine powder.
Sieve well and add the flour to the mixing bowl.
Heat a deep pan with oil for deep frying.
Clean pirandai and remove the veins and chop into pieces.
Take pirandai and green chilies in a mixie jar and grind coarsely.
Add ¼ cup water and grind to a smooth paste.
Transfer to a metallic sieve and squeeze the juice.
To the mixing bowl containing the flours, add salt and mix well.
Add 2 tsp hot oil from the pan. Mix well with your finger tips.
Add drained, soaked channa dal and mix well to distribute evenly.
Add the pirandai juice and knead to smooth dough.
Pinch lemon size balls and place it on a greased plastic sheet and pat into 3 to 4 inch thin discs.
You can also flatten the balls using the flat bottom of a tumbler or bowl.
Using a fork prick the thattais at 2 or 3 places on the surface.
Slip the thattais gently into the hot oil and deep fry till golden brown.
Gently flip them and fry till the sizzling stops over medium low flame.
Remove on a kitchen paper and let it cool completely.
Pirandai thattai is ready.
Store in an air tight jar to maintain the crispiness of the thattai.