How Long Should I Ferment Dosa Batter? In ideal conditions, you should ferment the Dosa batter for 8-10 hours. In the summertime, you may achieve good results within 6 hours as well. If you are living in a place where it snows heavily, you will probably have to think about a 12-15 hours fermentation period.
History of dosa says that they were made using only rice but with the passage of time, people started to add urad dal / black lentils to give texture and taste. Dosas became very popular with the rise of udupi restaurants which serve the best dosa varieties – plain, set and masala dosa.