Firstly add urad dal, chana dal & methi seeds to a large bowl. Rinse them very well several times and discard the water. Soak them together in enough fresh water for 4 to 5 hours.
Next add rice to another bowl and rinse a few times. Pour fresh water and soak in ample water for 4 to 5 hours.
Soak poha in ¼ cup water 30 mins before blending the batter.
Drain the water from the dal & methi. Add them to a blender jar along with salt, soaked poha and ¾ cup water. You can also skip salt at this stage if you live in a hot region. Add it to the batter just before you make dosas.
Grind to a smooth batter until smooth & bubbly or frothy. If needed add more water about 2 to 4 tbsps. It will be of thick pouring consistency and not very runny. Transfer this to a large pot.
Drain the water completely from rice & add it to the jar. Then pour ½ cup water.
Blend to a smooth or slightly coarse batter. It will be of thick pouring consistency and not very runny.
Pour this to the urad dal batter and mix well both of them well with your clean hand. Warmth in the hand will help in fermentation. The consistency should not be too thick & too runny otherwise the batter will not ferment. (Check video to understand the consistency)
Cover the pot and ferment it in a warm place until the batter rises and turns bubbly. If you live in a warm region, then you can just keep it on the counter overnight. It may take anywhere from 5 to 16 hours depending on the temperature.
To ferment in colder regions, preheat the oven at the lowest setting (140 F or 60 C) for 10 mins. Turn off the oven and keep the dosa batter inside with the oven light ON. You can also use your instant pot to ferment with the yogurt settings. Use an external lid and not the IP lid. I ferment for only 7 to 8 hours in the oven & IP.
Check if properly fermented: Well fermented dosa batter will rise & increase in volume. It will be frothy and bubbly. To check, drop half a spoon of this batter into a bowl filled with water. Well fermented batter will float & not sink.
Stir the dosa batter once. Transfer a portion of this to another small bowl to make dosas. Refrigerate the rest for up to 1 to 2 weeks.
The fermented batter usually becomes thick, so add little water good enough to thin it down. At this stage it has to be of a pouring consistency yet thick. (check video)
If making masala dosa, you will have to make this potato masala or any chutney from here.
Grease a dosa pan or tawa with few drops of oil. You can also rub the oil with a slice of onion. This prevents the dosas from sticking to the pan.
Heat it until hot enough. To check you can sprinkle little water over then pan. If it is ready it will sizzle.
Stir the batter well in the bowl. Take a ladle full of dosa batter & pour on the center of the hot griddle/ tawa.
Immediately begin to spread it evenly starting from the center in a circular motion in clockwise direction to make a thin crepe.
Increase the heat to slightly high and let it cook for a minute then add oil or butter towards the edges.
The edges of the dosa will begin to leave/ come off the pan when done. Continue to toast until the dosa turns golden and crisp.
Not all dosas need to be cooked on the other side. Only thicker ones need. If you wish to cook on the other side, flip it when the edges begin to rise from the pan. Cook on the other side of the dosa. Then flip back and toast until the base becomes crisp & golden.
Before making the next dosa, reduce the heat to low. You can also rub with the cut onion and then pour the batter.
Serve dosa with coconut chutney, potato masala & tiffin sambar.