Prepping batter: Mix together salt, sugar and dosa batter.
Prepping tawa or pan: Heat a non-stick pan or a seasoned cast iron dosa tawa over medium heat. Once hot, pierce the onion half with a fork, dip in oil & rub on the tawa. This prevents the dosa from sticking to the tawa.
Reduce the heat to low & pour one ladle of dosa batter in the center of the tawa. Spread by using the back of the ladle, moving in concentric circles to form a big round dosa.
Increase the heat to medium. Drizzle a spoon or two of oil or ghee around the edges and in the center, cover with lid & cook for 30 seconds.
Remove the lid and let this roast uncovered for a minute on low heat till the underside of the dosa gets light golden.
Spread mysore masala chutney all over the dosa, add a few bits of butter on the dosa.
Place about 2 tablespoons of aloo masala in the centre and flip one half of the dosa over it. Serve hot.
Follow the same steps for making the rest of the mysore masala dosas.