Boil 1 cup of water, salt as needed in pan. Now add 1/4th cup of Finger millet (Ragi) flour and make a thick porridge (batter). Switch off the stove. add rest of the Finger millet (Ragi) flour and make a soft dough like you do for chapati.
Now to the dough add onion, green chili, coriander leaf and press the dough so that they all mix well.
Now make small ball out of the dough and flatten them with rolling pin to a round thin sheet.
Heat the flat iron skillet or non-stick tawa pan with coat of oil.
Place the flatten raw adai. Sprinkle oil around it.
Once this side is cooked, flip over and cook until the adai dosai is cooked on the other side. Remove and serve