Wash the rice and lentils for at least 3 to 4 times and drain the water. Then soak them along with fenugreek seeds in sufficient water for about 6 hours. Then drain the water thoroughly.
In a mixer jar, first, add the cooked barley and pulse it without adding any water. Then add the rice and lentils little by little and pulse them by sprinkling water. After adding the entire rice, lentils, and fenugreek add water little by little and grind into a thick, smooth batter. Slightly coarse batter works too. I used about 1.5 cups of cold water for this measure. The water depends upon the rice and dal quality.
Transfer it to a cleaner vessel and add salt. Mix the salt and batter with clean hands and ferment it. Depending upon the weather, the fermentation time varies. Also, during summer, the mixture ferments fast as we are using cooked barley.
Right after the batter is fermented, mix it, and refrigerate it right away and use it within two days. For making idli, the batter should be thick and it should not be runny.
Pour about 1.5 cups of water in the idli cooker and let it simmer over medium heat. Meanwhile, grease the idli plate molds with 1/2 tsp oil and then pour the idli batter inside the molds. Place the idli trays in the steamer and close the lid.
Steam for about 12 minutes over medium heat and then turn it off. Wait for five and then open the lid. Using a wet spoon, carefully and gently remove the idli from the mold. Serve warm with chutney, sambar or idli podi.
For the batter should be in pouring consistency so if required add 1/2 to 1/2 cup of water.
Heat the tawa and ensure it is over medium heat.
Take a ladle full of batter and pour it in the center of the tawa and spread it lightly and slowly. Do not spread it too thin.
Drizzle 1/2 tsp of oil around the edges and let it cook until the color changes or the edges loosen up. It takes about 45 seconds to 60 seconds.
Then carefully flip the dosa and let it cook for just 10 to 20 seconds.
Remove it from the tawa and similarly make dosas with remaining batter.
I used coarse kosher salt for this you can add up to 1.5 to 2 tsps of fine salt for this measure.
The amount of water required depends upon the quality of rice and dal, so add as needed. Also, use one or two ice cubes as it prevents the batter from getting heated. I usually use cold water.
You can get more information about the cast iron pan dosa on my karaicha dosai post.