soak the urad dal for 1 hour and grind it, without adding water if need just spray the water and make as batter
chop the onion, green chili and coriander leaves
in a bowl add urad dal batter, onion green chili, coriander leaves, cumin seed, black pepper seed, maida, corn flour, rice flour and salt
mix well
heat the oil in the pan and fry the urad dal batter in vadai shape
medhuvadai is ready to serve