In a mixing bowl, combine sooji, besan, ground cumin & coriander, ginger, green chilies and salt.
Mix well. Add shredded vegetables, oil, yogurt and mix well. If the mixture seems too thick, add water little at a time to make a thick pourable batter. Set aside for 30 minutes.
When ready to make the handvo, stir in the baking soda into the batter and mix well.
Heat oil in a cast iron or other heavy base pan on medium heat. Add the mustard seeds, sesame seeds and curry leaves.
Once the seeds start to splutter, pour the prepared batter into the hot pan.
Cover and cook on low flame until the bottom is crispy and golden brown, will take about 10~12 minutes. Top of the handvo should be slightly firm at this point.
Carefully flip over and cook till the other side is crispy and golden.
Serve hot with green chutney.