First wash and soak the chana dal and urad dal together in water for about 1 hour. Then drain the water and keep aside.
To a large mixing bowl, add all the ingredients listed (including the soaked dal) except for Oil. Mix well until all ingredients are combined. Now start adding water little by little and mix to get a smooth non-sticky dough. I used close to a 1 ½ Cup of water. Keep the dough covered with a wet towel until use.
<br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-1.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-2.jpg" alt="that" width="48%" />
Now heat a pan with the oil for frying. Take two pieces of banana leaf or thick plastic sheets (I used zip lock covers). Grease them with oil. Now take a medium gooseberry size of prepared dough and make it into a ball. Keep the remaining dough covered to avoid drying of dough. Place the dough ball on the greased plastic sheet.
<br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-3.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-4.jpg" alt="that" width="48%" />
Now, place the other greased sheet over the ball, press it into a thin flat disc. I used a flat base vessel. Now remove the top sheet and use your fingers to even out the thattai. Prick the thattai using a fork to avoid puffing up of thattai while frying.
<br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-5.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-6.jpg" alt="that" width="48%" /><br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-7.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-8.jpg" alt="that" width="48%" /><br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-9.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-10.jpg" alt="that" width="48%" />
Remove the thattai from the sheet gently and slide it into the hot oil. Cook in medium-low flame by flipping the thattai at regular intervals. Fry until the bubbles totally subsides / stops and the thattai becomes golden brown on both sides. Remove from oil and drain excess oil on a paper napkin. Repeat the same with the remaining dough.
<br><br><img src="//revisfoodography.com/wp-content/uploads/2017/02/that-11.jpg" alt="thattai" width="48%" /> <img src="//revisfoodography.com/wp-content/uploads/2017/02/that-12.jpg" alt="that" width="48%" />
Store in a air tight container once completely cooled down. Enjoy as an anytime snack.