Soak rice with all dals in five cups of water for two hours. Drain. Grind to a coarse paste and add water to make a batter of medium thick consistency. Mix in yogurt and a teaspoon of soda bicarbonate.
Cover batter and keep in a dark place for two to three hours so that it ferments. Add salt, sugar, red chilli powder, turmeric powder to the batter and mix.
Preheat the oven to 200°C. Heat oil in a pan, add whole red chillies, bay leaf, asafoetida and mustard seeds. Sprinkle remaining soda bicarbonate on batter and pour lemon juice on it. Immediately pour hot tempering on this and whisk briskly.
Grease small moulds. Pour batter in each till half full. Put some water in a baking tray and place the moulds on it.
Cook in the preheated oven at 200°C for twenty to twenty five minutes. Demould the handvo. Serve with green chutney.