Put the onion, garlic, green chilies and coriander with half the water in the blender and blend to a fine paste.
In a bowl mix together the besan flour, dhaniya powder, zeera, garam masala, chili powder, salt and soda.
Add the blended liquid and rest of the water and mix well to forma thick paste.
Put in the chicken pieces and mix well so that the chicken is well coated with this mixture.
Deep fry in hot oil till golden brown. Serve with ketchup or mint chutney.