To make Thayir vadai, add the drained vadai in a bowl of hot water. Let it soak 5 mins. Then, drain off the water by squeezing the vadai gently so that it doesn't break and transfer it to another bowl. Add in thick curd/yoghurt in the bowl with the vadai and season it with small gratings of a carrot along with back mustard seeds sautd in oil and chopped cilantro.