Wash the toor dal, channa dal, urad dal and rice and let it soak along with red chili and green chili for at least one to one and half hours.
Similarly, wash the moong dal and let it soak separately.
After 1.5 hours, drain the water and grind it along with turmeric powder, hing, and ginger. Sprinkle some water while grinding. I used only 2 tbsps of water while grinding. Take this ground vada batter in a wide bowl.
Add two more tbsps of water to the mixer jar and rinse it. I added one tsp besan and mixed in the mixer jar itself.
Add this besan water to the vada batter. Then add the drained moong dal, salt and curry leaves.
Now in a tempering pan, heat the one tsp of oil and once it is hot add the mustard seeds. When they splutter add the same to the vada batter.
Then add the coconut and cilantro as well.
Mix them all and add ¼ cup of water and mix again.
The consistency should be like as shown in the picture. It should be thick but still in pouring consistency.
Meanwhile, heat the oil for frying the vada.
Once the oil is hot, take a ladleful of batter and slowly pour in the oil.
Let it fry for 40 seconds and flip and let it cook until the bubble ceases and it turns crispy.
Make the vadai with remaining batter similarly.
That's it. Thavala Vadai is ready. Serve hot with chutney and tea or coffee.
Notes
The steps might sound lengthy, but all you need to do is soak the lentils and rice. Grind them, add the remaining ingredients, temper, and fry.
The proportion formula is - you need to take an equal amount of channa dal, urad dal, toor dal and rice and half the amount of moong dal. You can adjust other ingredients as per your preference especially the salt and chili.
Grated coconut and soaked moong dal adds a distinctive texture and do not skip them.