Wash and soak the Urad Dal for 2 hours. Drain the water used for soaking.
Grind the Urad Dal along with green chillies, ginger into a thick batter consistency (using water as required).
To the ground urad dal batter, add salt to taste, hing and rice flour. Rice flour is added for crispiness (since we are not going to deep fry). Beat the batter well for a couple of minutes until its soft in texture.
Heat an appe pan or paniyaram pan. Add oil and slowly pour the batter into the small shallow holes of the pan. Cover and cook on low heat
Flip, add few drops of oil, cover and cook again until the vadas have cooked in the centre.
Take 2-3 cups of water in a bowl and add these piping hot vadas into them. The vadas will turn softer. Gently squeeze the excess moisture and keep aside.
In the meanwhile, repeat the process of cooking the vadas in appe pan, adding them in water, squeezing and keeping aside until the batter has been used up.
Whisk the curd well, add some water to get the desired consistency. Add some salt.
Soak the vadas in the dahi mixture and add grated carrots, coriander leaves. Prepare for tempering.
Pour the tempering over the dahi vadas, garnish with finely chopped coriander leaves, sprinkle some red chilli powder and enjoy it chilled.