Soak ½ cup of Chana Dal and 1/4 cup of Urad Dal for at least 3 hours.
Drain the water and grind the dals coarsely in a mixer.
Transfer the ground dal to a bowl and add chopped onion, carom seeds (ajwain), coriander-cumin seeds powder, asafoetida (hing), turmeric powder, crushed green chilli-ginger-garlic-cumin, coriander leaves, and salt.
Mix all the ingredients well.
Add a little water to the mixture and beat it lightly for 2-3 minutes.
Add a pinch of cooking soda and mix gently.
Heat oil in a pan.
Drop small portions of the mixture into the hot oil and fry until golden brown.
Remove and serve hot.