Apply tamarind water to the hands n peel the Maaddi/ colocasia tuber, cut them into roundel's n slice them n only now wash them as Once the maaddi comes in contact with water, it itches your hand. So wash it after you chop it .
Pressure cook the colocasia slices with salt and just little water for just one whistle or just before the whistle ..as maaddi should be cooked but not overcooked n mushy . Drain the water n allow it to cool n dry completely .
. In a bowl, add red chilly powder ,hing, turmeric powder, Rice flour ,salt n mix well. Add the cooked maadi slices into the bowl one and by one n gently mix n set aside for few mts .
Heat a dosa tawa , add little oil . Run the marinated maaddi slices over semolina n place around 4 to 5 on it n shallow fry on both sides till crisp.