In a large kadai / pan , take sour butter milk . Keep the flame on low .
If you don't have butter milk, add a cup of sour curd and add half cup water, whisk and add.
To the buttermilk add cumin, hing , chopped curry leaves, coriander leaves, green chilli and salt. Mix well. Let the flame be low on only .
Bring the flavored buttermilk mix to boil . Let ot boil for 1-2 mins .
Add rice flour to it slowly . Add a tsp of oil . Do not mix the flour .
Simmer the flame and cover for 2-3 mins.
Now mix rice flour well with buttermilk , slowly in 2-3 mins you will see that all water content has absorbed and slowly it starts forming a dough.
When a single lump dough is formed, done .
transfer the dough into a large mixing bowl and allow to cool slightly. When the dough is still warm , knead the dough nicely to form a soft non-sticky smooth dough.
Now, heat idhayam mantra oil for deep frying in a kadai or pan on medium flame.
Next roll kodubale.Take a lemon size dough,gently roll on a flat surface to make a thick rope like and press the ends to form a ring.Press it well to seal the edge.Similarly make about 8-10 rings and keep aside.
Once the oil is hot,gently drop the ring into hot oil in batches .
Deep fry them on medium low flame on both sides till they turn crisp.Once done, remove from oil and transfer to a paper towel.