Ingredients 

For Vadas

• Urad dal 1 cup
• Moong dal 1/4 cup
• Salt 

For Dahi

•  Dahi  5 cups
• Green chillies, chopped 1 tsp
• Ginger grated 1/2 tsp
• Curry leaves 
• Mustard seeds 1/4 tsp
• Asafoetida pinch
• Salt 
• Sugar 4 tsps

For Vadas

• Soak the two dals for 7-8 hours or overnight. 
• Grind it to a smooth paste. 
• Add salt to taste. 
• Heat oil for deep frying in a frying pan and add spoonfuls of dal batter and fry until the vadas are golden brown. 
• Drop the hot vadas in a bowl of cold water and leave for about 3-4 minutes. 
• Take each vada out from water, squeeze the water out and set aside. 

For Dahi 

• Blend the yogurt with little water until it is smooth. 
• Add sugar, salt, green chillies and ginger. 
• Make a tarka (seasoning) of mustard seeds, asafoetida and curry leaves and add to yogurt. 
• Keep the yogurt in refrigerator until it is chilled. 

• Arrange the squeezed wadas in a deep dish.
• Pour the yogurt on the wadas such that all the wads are covered well by the yogurt. 
• Sprinle red chiili powder, roasted jeera powder and black salt