Mix wheat flour, salt and water to make a lump free batter.
heat oil and splutter mustard seeds, urad dal, curry leaves, cumin seeds, chopped onions along with chilli powder.
fry for half a minute.
add the fried onions tempering to the batter.
mix well and add little water if needed.
heat the dosa tawa to medium heat.
spread the batter to a thin disc.
sprinkle oil on the sides. cook on both the sides.
serve hot with red chilli chutney.