Rice can be soaked for 3-4 hrs, dried and powdered in a mixer. Mix rice powder, a little water and knead it with spatula on slow fire till it becomes thick and leaves the sides of the pan (good enough to make dough). Cool it for a while.
Roast black dal till reddish, cool it and powder it very finely in a mixer.
Add dal powder, all other ingredients to rice paste and knead it into a very smooth but firm dough.
Fill the dough into a chakli making press with seaves for thenkuzal. This is most common hand-held tool for making chakli in South India. If you don't have the exact one, you can use any sev making tool for the purpose. It must have bigger holes than those used in normal sevs.
Carefully make circular motions with the press while pouring into a hot pan of cooking oil.
Deep fry the thenkuzal in median heat.
Remove and cool it. Thenkuzal is ready. Well made thenkuzals are hollow inside.