You will need to have near your skillet: ¼ to ½ cup of vegetable oil in a cup or bowl with a small spoon, a larger spoon to spread the batter, the bowl of batter with a ⅓-cup measuring scoop/cup, a metal spatula for turning the pancakes, and a plate on which to place the finished dosas after they are cooked.
Pour 1 teaspoon of oil into the skillet and tilt to distribute evenly.
Heat the skillet over medium-low until oil is hot.
Pour ⅓ cup of the mixture onto the center of the hot skillet.
Use the large spoon to spread the batter in a spiral motion, until the pancake is about 6-7 inches in diameter.
Turn pancake after 2–3 minutes and cook another 2–3 minutes on the other side.
Remove pancake to plate and repeat with remaining batter, adding only enough additional oil to the skillet as needed to keep surface evenly greased.
I found that about ½ to ¾ teaspoon for each pancake was plenty, but your mileage may vary.