In a mixing bowl, combine ragi flour, rice flour, salt, and water to make a thin batter. Mix well to remove any lumps.
Cover the bowl and let the batter rest for 4-5 hours or overnight.
Heat a non-stick tawa or griddle over medium heat.
Pour a ladleful of batter onto the tawa and spread it in a circular motion to form a thin dosa.
Drizzle oil around the edges of the dosa and cook until the underside turns golden brown and crispy.
Flip the dosa and cook for another minute or two.
Serve hot with coconut chutney or any other chutney of your choice.