In A Short Course in Culinary Experiments, the dosa and idali batter are prepared with long grain rice (also called as raw rice). You can prepare the idali batter with a different protocol, which will result in puffier idalis. The suggested modification in the ingredient list is as follows:
1. Urad dal: 1 cup
2. Long grain rice: 2 cups
3. Parboiled rice: 2 cups
4. Flattened rice: ½ cup
Soak urad dal overnight in water. Rice varieties 2 & 3 can be combined and soaked overnight in water. Flattened rice (poha) has to be soaked overnight in water, separately. The grinding protocol can be same as described in section ST5. The flattened rice can be added towards the end of the grinding process of the two rice varieties. The resultant batter will produce more puffy idalis.