Start by soaking a small lemon size tamarind in water for 10 minutes. Squeeze the tamarind with water and extract the pulp. Strain the tamarind to get tamarind pulp. Take tamarind pulp in a large kadai or pot which can hold the rasam and vadai. Add more water as per required. I used around 3 cups of water. Add in 1 tablespoon of roasted cumin powder and 1 tablespoon chilli powder. I also added a good dash of asafoetida (around 1 tsp). Add salt to taste and lots of crushed garlic. I crushed a whole bulb of garlic with their skins on in a mortar and pestle and added those. I like to use lots of crushed garlic which adds wonderful flavour. Add a handful of curry leaves and bring it to a boil. Taste and adjust the salt, tamarind and spice level accordingly. Keep this warm and set aside.

Soak chana dal for 2 to 3 hours. Strain it completely. Add it to blender and grind coarsely. Now add salt and other ingredients except oil and mix well.

Take small portion and flatten it slightly. Fry it in hot oil till golden and crispy. Strain using slotted spoon and set aside.

Add the fried vada in hot rasam and simmer for 10 to 15 mins Now turn off the heat and cover the pot, soak it for 1 to 2 hours. Serve hot.

Wash and Soak channa dal and urad dal for at least 2 to 4 hours. Strain them and add it to a blender or grinder and make into a fine paste. Don’t add too much water, add water slowly and grind this till the batter is nice and fluffy. Since there is urad dal, the batter will foam up while grinding. You need that, this will make the vadai melt in your mouth. Once you have ground, add curry leaves in it and mix well. You don't need to add salt.

Heat oil for deep frying and drop small vadai in oil and fry them till golden. Strain them and set aside.

Now add this to hot rasam. Switch off the flame and let it sit for 15 to 20 mins till they are soaked. Serve warm or hot.