Clean, wash and soak the dals, rice and whole wheat together in enough water for atleast 4 to 5 hours. Drain and keep aside. Blend the dals, rice and whole wheat in a mixer to a smooth mixture. Transfer the mixture to a bowl, add the curds and mix well. Cover and keep aside to ferment overnight. Add the bottle gourd, 1 tsp oil, lemon juice, soda bi-carb, 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 sauté 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. Repeat the steps 7 to 11 to make one more handvo. Serve immediately.