To begin, prepare the badis. Take gram flour (besan) in a bowl. Add carrom seeds (awain), salt, red chilli powder, and turmeric powder. Add in water in batches to make a thick paste of dropping consistency. Beat well to aerate the batter so that the badis are soft and fluffy.
Heat oil for deep frying. Drop the batter into hot oil to make small badis. Deep fry until slightly golden. Remove and keep aside.
In another bowl, whisk together the curd and besan.
Heat mustard oil in a pan. Add in the cumin seeds, fenugreek seeds, and asafoetida (hing). Allow them to crackle.
Next, add the ginger garlic paste with chopped green chillies. Saute for a minute.
Now add the curd and besan mixture you prepared earlier. Mix well. Allow it to come to a boil, stirring constantly, or the kadi will clump together.
When it comes to a boil, add the salt and turmeric powder. Mix well. Reduce the heat and let it cook for around 10 minutes until it is nice and creamy.
Add in the badis and garam masala powder. Mix well. Cook for a few more minutes.
Transfer the Kadi Badi to the serving dish.
Prepare the tempering. Heat oil in a tempering pan. Add in cumin seeds, red chilli powder, and whole red chillies. Pour this tempering over the kadi.
The Bihari-Style Kadi Badi is ready to serve. Serve hot with boiled rice.