Clean, wash and soak the daals, rice and whole wheat together in enough water for at least 4 to 5 hours. Drain and keep aside.
Blend the daals, rice and whole wheat in a mixer to a smooth mixture.
Transfer the mixture to a bowl, add the curd and mix well. Cover and keep aside to ferment overnight.
Add the bottle gourd, Carrot grated, Cabbage shredded, 1 tsp oil, lemon juice, soda, sugar, chilli powder, turmeric powder, ginger-green chilli paste and salt and mix well. Keep aside.
Heat the remaining 2 tsp of oil in a non-stick kadhai and add the mustard seeds.
When the seeds crackle, add the sesame seeds, carom seeds and asafoetida and saute on a medium flame for a few seconds.
Pour half the batter evenly to make a thick layer.
Cover and cook on a slow flame 9 minutes or till the base turns golden brown in colour and crisp.
Lift the handvo gently using 2 large flat spoons and turn it over to the other side.
Cover and cook on a slow flame for another 7 minutes or till it turns golden brown in colour.
Cool slightly and cut into square pieces.
Serve with chutney and chach.