Take 1 cup of urad dal and wash it thoroughly until the water is clear. Soak the lentils overnight or for a minimum of 6 hours.
Dry grind the soaked urad dal with few tablespoons of water as needed.
Grind to a smooth paste and make sure to grind in 2 or 3 batches and not all at once.
Remove in a large mixing bowl and add ¾ teaspoon salt or as per taste. Whisk the vada batter for 5 to 7 minutes in the same direction. This step is done to make the batter airy and light.
Then add 1 teaspoon whole cumin, 1 teaspoon chopped ginger, chopped green chilies as per taste, and mix well. Set aside for 30 minutes.
Heat enough cooking oil for deep-frying vadas in a wok. Take a tablespoon of batter with a hand or spoon and drop it into the medium hot oil. Fry all the vadas in batches and remove them on a kitchen tissue.
Take a bowl of clean warm water and soak all the fried vadas for 15 minutes or until they are double in size. After soaking, squeeze out all the water and place the vadas on a serving dish or tray.
Pour a generous amount of sweet & spicy yogurt over each vada. Sprinkle some chili powder, cumin powder, and chat masala powder. Top it with Mint chutney and spicy green chutney.
Serve chilled as a snack.