1-2tspSesame oilfor greasing the moulds ( you can use any other oil too)
Instructions
Soaking
Wash the rice well a couple of times and soak it with water about an inch above the level of rice.
Wash and repeat the same with urad dal also.
Let these soak for about 3-4 hours.
to make the batter
in a wet grinder add the urad dal which has now plumped by soaking. Add just enough water(water from soaking) to make a smooth paste.
Grind to a smooth fluffy paste.
Remove into a large vessel and set aside
Drain the rice, reserve the water and grind to a smooth paste just like the urad dal
Add the rice paste to the already ground urad dal and mox the two together very well.
Setting for fermentation
The mixed batter should just occupy half to three fourth of the vessel of choice so that it doesnt over flow.
Now set this batter covered in a warm corner of the kitchen, undisturbed overnight ( 6-8 hours ,depending on the weather)
The batter will rise and ferment.
for steaming
Add salt anout 3/4 tsp and mix the batter well.
The batter should now have a pourable consistency like honey and not like water. If thick adjust by adding a bit of water.
Grease the moulds with oil and set aside
Set the steamer vessel with water.
Pour a ladle ful of batter in each mould (approximately 3/4th of the mould)
Set the moulds in the steamer
Bring the water in the steamer to a boil and steam for 10 minutes(15 if using ramikens)
Let the mould stand in the steamer for another 10 minutes ( motherin laws
's expert advice) this helps to unmould without tears.
Unmould the idly one by one by using a butter knife or a small flat spoon to loosen the edges.
Serve hot with chutney, sambhar or podi or all of these.
Notes
There are recommendations for mixing the batter by hand before fermenting. But being a microbiologist by education, I feel this will be a tad bit over as skin bacteria is not what you are looking to ferment the batter, but the airborne harmless ones. Hence I don't follow that.It can become very difficult to get the fermentation in winters, here is a recommendation from a friend- add in a couple of tbsp of previously fermented batter ( last weekly prep ) to the one you are freshly doing, something on the lines of a starter culture.Adding salt before fermentation is purely a matter of personal choice, my mother in law doesn't recommend it and I go by her experience.If the weather is cold, it is a brilliant idea to set the prepared batter in the warm oven with the oven lights on, just for warmth.The batter stays well in the fridge for a week. Don't leave it out for long in warm weather as it tends to turn sour due to over fermentation.The Indian grocery stores will carry just skinned urad dal and skinned and split urad dal. My mother in law insists on the skinne, bead-like one rather than the split one. in my experience, the split one doesn't rise well and leads to harder idlies. I don't have a logical explanation for this, but this is my experience.