Clean Urad dal and Methi, wash then soak them in water for 4 hours or the entire night. Clean rice, wash and soak it in a different bowl for the same amount of time.
Remove water from the soaked dal and grind Urad dal-Methi with little water to make a fine paste then put it in a big bowl. Similarly using very less water grind the rice, but make a bit thicker paste. Mix the 2 pastes together and prepare a thick mix which when poured with a spoon does not fall freely.
Add salt and baking soda to the mixture allowing it to ferment, cover and keep aside for 12-14 hours. Fermented mixture doubles in quantity. This mixture is ready to make Dosa.
Prepare spices for Dosa
Boil potatoes, cool them off then peel and break them into small pieces.
Heat oil in a frying pan(kadhai), put Rie in hot oil and roast. Now put turmeric powder, coriander powder followed by green chillies, ginger and fry for 1 minutes. Add peas and 2 tbsp water then cover the pan and cook till peas turn soft. Put potatoes, salt, Amchur powder, red chilly powder in the pan with spices and fry for 2 minutes. Turn off the gas then mix coriander to the fried spices. Spices required for Dosa are ready.
If you want to put in onion then finely chop 1-2 onions, ginger, green chillies. Fry all the ingredients till they turn light pink, mix the other contents as instructed earlier and make the spices for Dosa.
Stir the mixture with a spoon, if it seem too thick then add some water(mixture should be a bit more thin than the mix for pakoras).
Heat a non-stick pan or a heavy flat pan(tawa) to make Dosa, when the pan is sufficiently heated keep a medium flame. Now wipe the pan with a thick wet cloth, first grease the pan with little oil(pan should only look smooth, oil should not be seen). Pour a big spoon full of mixture in the middle of the pan, move the spoon in round circles as you spread a thin layer of Dosa(12-14 inches in diameter) on the pan. Pour little oil with the spoon all around the Dosa.
Cook Dosa on a medium flame, when the upper layer seems cooked even the layer below turns brown. Now place 1-2 spoon of potato with spices on the Dosa and spread it all over. Using a ladle pick Dosa from the edges and fold it, take it put of the pan and place on a plate. For the next Dosa pour 1 spoon full of mixture in the pan and spread it all over, follow the same process to cook the Dosa. All Dosas are to be made in this same manner. Serve hot Dosas with Sambhar and groundnuts Chutney and eat..
Mixture has to be spread in the way instructed above, potato with spices mix should not be kept on the Dosa, lift this Plain Dosa from the edges, fold and serve.
To make Paper Dosa the mixture has to be made more thin compared to that of Plain Dosa, mixture should be spread on the pan very thinly and it has to be cooked like Plain Dosa.
Grate Paneer, add salt to taste and chopped coriander instead of potatoes, put 1 tbsp Paneer on the Dosa then fold and serve in the same manner.
Note :
1. Before you spread put the mixture do not forget to wipe the pan with a wet and thick cloth.
2. Heat the pan sufficiently before you spread Dosa mix on it.
3. Before you fold the Dosa cook it's lower layer till it turns brown.
