Keep urad dal, chana dal and rice to soak in water for 12 hours. Now strain it and after straining mix it in mixer grinder.

Now put baking soda and again keep it 12 hours now add salt to paste.

Take some oil in a pan add rai, curry leaves, chopped onions, turmeric powder, amchur powder and saute it for 2 mins.

Now crush potato and add it in a pan. Now take a non stick tawa put some oil and add 2l4 tbsp batter and spread it thoroughly

Add potato masala to it and fold it. Now put garlic, tomatoes and red chilli and grind it in mixer grinder now add salt to it

In one pan put some ghee and saute it for 3 mins for sambhar recipe see sambhar idli recipe now your dosa is eady to serve.