DESCRIPTION:      Dahi Vada is a popular snack in India. It is prepared by soaking vadas (fried flour balls) in thick dahi (yogurt). Dahi Vada is also known as dahi bhalla in Punjabi, thayir vadai in Tamil, thairu vada in Malayalam, perugu vada in Telugu, mosaru vade in Kannada, dahi bara  in Odia and doi bora in Bengali. In North Indian version Dahi vada, they are served with green chutney or saunth( tamarind sauce ) sprinkled with some spice mix.      PREPARATION:      Preparation time: 9 hrs   Cooking time: 45 mins      INGREDIENTS:      For making vada (35-38 small vadas)   -1 cup urad dal   -1 green chili - chopped    -½ inch ginger - chopped    -1 teaspoon cumin seeds    -1 pinch asafoetida    -3 tablespoon water for grinding the                batter or as required   -salt as required    -rock salt        For dahi vada:   -2 to 2.25 cups curd    -½ to 1 teaspoon chaat masala or as               required   -¼ to ½ teaspoon red chili powder or as        required    -1 teaspoon roasted cumin powder    -black…