Soak the Toor dal in water for half an hour and pressure cook Toor Dal ,Onion and Tomatoes with water for about 4- 5 whistles or until the Toor dal is cooked. Wait until the pressure get released by itself. Now open the pressure cooker and mash the cooked toor dal and vegetables finely. Next add in the Sambar powder, Turmeric powder and Chilli powder and mix well. Now Take a kadai/Pan and add in oil or Ghee.
Once the oil becomes hot add in the ingredients in order from the “To Temper “list .Fry for a min until you get a nice aroma and then add in the Sambar mixture, Add in Salt and Tamarind water and wait until the Sambar boil, Once the Sambar boils well and the desired consistency is reached add in the freshly grated coconut and finely chopped coriander leaves. Switch off the flame.
Wash and soak urad dal for about 3 hours and then without adding water grind it into a smooth paste .Chop all the vegetables finely and set aside.
Add in the chopped vegetables to the ground urad dal add pepper corns and salt and mix well. Now heat oil in a Kadai for deep frying.
Make sure the oil is very hot drop a small piece of batter and check if it comes to the top this is to confirm the oil is hot enough for frying. Now grease your hands well and take the batter in your hands in the shape of vada. With the help of thumb make a hole in the center of the vada. Drop in the oil for deep frying.
Do not flip the vada immediately it might get crumbled .Fry till the vada turn golden brown and crisp. Drain in Paper towel.
Now time to assemble the Vadai and Sambar .In a large bowl take water ,Soak the vadai in water and then remove the vadai from the water and squeeze out the water and arrange in the serving plate
Repeat this process for all the vadai ,Now pour hot sambar over the vadai and let the vadai gets fully soaked in sambar ,Allow it to rest for about 10 mins and then garnish with finely chopped onions and serve hot.