Wash and soak urad and chana dal in water for about 2-3 hours.
Drain the water from the dal and make a paste by grinding the dal in a mixer. The consistency of the batter should not be too thin as the vada needs to be shaped before frying.
Add coriander, green chillies, ginger, dried coconut, salt, hing (asafoetida) and rice flour to the batter. (Rice flour is very important as it makes the Vadas crunchy)
Take the batter on your palms and make small-sized circles, create a hollow in the centre to get the authentic vada shape.
Fry these Vadas in oil until they turn golden and crispy. Serve along with hot sambhar and chutney and enjoy your authentic South Indian Medu Vadas!