Measure all the ingredients and soak it in a wide bowl with enough water till immersing level. Soak this for atleast 3-4 hrs.
Rinse it well, then wash it well at least twice.
Then grind it to a thickish batter with little water. The batter consistency should be neither thick nor thin. I grinded it in my wet grinder, you can do it mixie too but grinder is recommended.
Add required salt, mix it and keep it undisturbed for it to ferment.
Leave it in warm place for at least 8 hours, I left it overnight. See the fermented batter the next day, it has raised well.
You can see the texture, mix it once then add water to make the batter thin.
Adjust and add water till it is in pour-able and spreadable consistency.
Heat a dosa tawa, if you sprinkle water it should give shh sound then the tawa is hot, now add 2 small ladle full of batter and spread it in concentric circles. Drizzle oil over the sides and in the middle.
Cook till it becomes golden in the center and the edges starts lifting up, flip to other side and cook for 2mins turn again flip over and fold it. Remove from tawa and serve.
Serve Chola Dosa hot with chutney and sambar.