Soak rice and dal separately for 4 - 5 hours, strain it and blend to make a paste. Add grated lauki,grated carrot,salt,sugar,curd,red chilly powder,turmeric powder,grated ginger,green chilly,coriander leaves,baking powder and lemon juice. and mix well. Fermentation for 10 to 12 hours Heat oil in a pan add black mustard seeds,cumin seeds,asafoetida and curry leaves to crackle. Add the batter of handvo into the pan and spread it. Cover it and cook in a low flame for 15 mins. Flip it and now cook cook for fifteen mins in low flame. Cut the pieces and serve hot with tomato ketchup.