How to make Idlis | Soft Idli recipe
1. Addition of Fenugreek Seeds (Methi)
Though not really necessary, adding Fenugreek seeds helps to aid fermentation. So add in about 1.5 tsp of Methi seeds (my ratio of rice and urad is 3:1).

2. Grinding Separately
The Rice and Dal has to be ground separately. This results in increase in volume and also aids in fermentation.

3. Using Filtered Water
Use non-chlorinated and/or filtered water since chlorine inhibits growth of wild yeast which is essential for fermentation.

4. Using Soaking water to Grind
Though I have no scientific reason to back this theory, from my personal experience, I find that using soaking water (in which you soak your urad dal and rice) to grind the batter also helps to aid fermentation.

5. Adding enough Salt
At times, not adding enough salt to the batter after its ground can also be a reason for lack of fermentation. Try to add at least 1/2 tsp (my mother mother suggests 3/4 tsp- 1 tsp) for every 1 cup of dry ingredients (rice +urad dal). You might probably need to adjust later according to your taste.

UPDATE: Though I have heard many say this as a point, I personally find NOT adding salt after grinding aids better fermentation since salt is actually an yeast inhibitor. I add salt only after it ferments. If you have tried other tips without success, then give this one a try.
6. Avoid adding ferment inhibitors
Avoid adding ingredients like Baking soda, Baking powder and Yogurt before the batter ferments since these inhibit the growth of wild yeast. If you really have to, add them after the process of fermentation.

7. Consistency of the batter
Adding too much water or too little will hinder fermentation. Give the batter a good stir with your hands instead of a ladle. The warmth from our body will help to kick start the fermenting process. Your end batter should have the consistency of ketchup, flowey, smooth and velvety in texture.

8. Fermentation Temperature
Ideal temperature for fermentation is 80-90F. If you live in a warmer place, then your fermentation should take place around 8 hour mark.

If you live in a place with cold climate you would have to take the following precaution:
  • Place your vessel with the batter in a warm, draft free place. Mostly this should be in a pre heated oven (switch off the oven though). Leave the Oven light on since it will give enough heat to keep the temperature steady throughout the fermentation period (mostly overnight). This should take about 10-12 hours.
  • You can also wrap a shawl around the vessel to keep it warmer. Make sure to use a huge vessel (which would accommodate even the doubled up volume of the batter) in that case. If fermentation occurs, your batter might overflow spoiling your shawl.
  • At times, if you use a room heater, placing the vessel in that room would help in fermentation.
  • I saw an idea where someone used a heating pad to proof their bread. I assume, the same method might also help in fermentation as well.

9. Avoid over sanitizing the environment
Over Sanitizing our houses (air filters etc) along with closed windows throughout the day, inhibit the growth of wild yeast in the batter leading to lack of fermentation.

10. Avoid using Air tight lid while fermenting
Do not close your vessel with the batter with an air tight lid. Instead simply loosely cover it with a plate or a cloth.

How to make Idlis | Soft Idli recipe

Last Resort (if above doesn't work)

There are three things you can do in such a case.
- Use a different Rice and Urad dal. They might be contaminated or old. Also try to opt for Whole Skinned Urad (namely Urad Gota) instead of split.
- Try a different recipe.
- Use yeast. I recall noting this info from a website (source forgotten, will update later) where they suggest using half tsp of yeast in half cup water and a teaspoon of sugar and then adding it to a gallon of batter.

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By Selvaraj on Jan 10, 2021

I saw from a lady Babes Projects, from usa, after many trials now buy fresh yeast , take half teaspoonful of fresh yeast mix with warm water little bit then add to idli or dosai batter, mix well put into a pre heated oven, keep underneath 1 big plate so that the does fall within a plate, im from melbourne, started recently, i plain dosa costs AUD 11.50, NOW WE CAN MAKE NICE IDLI DOSAI, ADD 2 TABS OF BARLY OR IN TAMIL IT CALLED SAVARISI, GRIND TOGETHER WITH RICE U WILL GET THE IDLI COLOR LIKE MALIHAPU, GOOD WHITE COLOUR.

By Pooja on May 24, 2019

The easiest way to ferment is to place the bowl of batter in a bigger vessel filled with hot water. If needed change the water after a couple of hours so that it doesn’t get cold. I have managed to ferment my batters within 4-5 hours in peak winter in Montreal with this technique

By Deepthi on Apr 29, 2018

Soak 2 tbsp of quinoa or millets like ragi or jowar along with udad dal and rice.. it wiill fernent

That's interesting! Will give it a try next time. Thank you for the tip Deepthi :) --DK

By Deepthi on Apr 29, 2018

Add 2 tbsp of quinoa to the dosa things while soaking or you can add millets like ragi or jowar etc.. while you soak and remaining process is same. It will definitely ferment.. i live in cold place. This is working ..

By Akhila on Mar 4, 2018

Hi dear So nicely written. Very nice explanation. Thanks for helping others About the urad soaked water helping in fermentation. The urad outer layer has the bacteria needed for fermentation. While soaking they get activated and grow so obviously soaked water will have it so aids in fermentation God bless Keep the great work going

By Domaraj on Jan 10, 2018

Hey folks. I am in ( northern) France, married to an indian man from Tamil Nadu I love idlis and cannot get enought with this little rice sponge. Yum yum...

By Abhiksha on Dec 21, 2017

I have soaked fr 4.5hrs..grinded after 4hrs but my batter is not properly it has rawa size rice in it.which I realised while adding the warmth of my hand..will my batter ferment well?

I don't think it will. Just grind it some more time until smooth. --DK

By Anuradha Phatak on Dec 16, 2017

I am in Michigan. Its second time my batter is not fermented. I took 3 cups of rice 1 1/2 Idli Raw rice and 1 1/2 cups Punni Boiled Rice for 1 cup of udad gota and 1/2 tea sp. of Methi dane in it. I grind them separately after 5 hours of soaking and added salt about 1/2 tea sp. Kept for fermentation in the microwave with its door open so the light init stays on.My oven light is too powerful so I feel the batter will get somewhat cooked? Till late in the morning next day it was just as it was and not fermented though I could see some lightness of the batter or small bubbles but not risen really as it often does? Where did I go wrong?

By usha gowri on Nov 29, 2016

I am left wondering about the pre heated oven.I believe it will half cook the dough and wont allow the idli to puff up on cooking.Any form of heat will kill the batter.We use a teaspoon of oil,sugar and salt and beat it in the batter .Leave it for overnight.Works like baking :-)) soft and spongy idlis

Your preheated oven should not be too hot to kill the rising. It would be just warm enough to mimic around 80F temp. I follow that method and have had an overflowing idli batter every time --DK

By Wyandotte on Nov 22, 2016

Your checklist is quite thorough. Good work! I tried to make idli for the first time, following all the recommendations and, yes, it did NOT ferment at all. What I don't understand is this: can we add yeast after a failed fermentation? I live in a cold climate. What do we do with our unfermented batter? That is a lot of good food going to waste if I have to throw it into the garden (for composting)! Thanks for your help!

By akashdeep on Sep 5, 2016

difference in cooking time texture and appearence of idli prepare by fermented batter and unfermented batte please explain

Different recipes have different outcome. The texture is dependant on the recipe. Rava Idli would be more porous, the ones made out of idli a little more dense, if using leavening (like eno fruit salt) more spongy etc etc. At the end of the day, you should have a light, chewy and not too dense steamed idlis - irrespective of the type. If its too dense, doughish, hard, rubbery then the mistake could be either the recipe itself or the process. --DK

By Rehana on Apr 27, 2016

Hi DK, Please may I have your email id to send you my questions on the idli fermentation. Thanks.

By Jayakumar R (Mr) on Mar 29, 2016

Very impressive list! Good work. Thanks. Let me try one of these ideas. We live in Singapore (warm always) still we have an issue with Fermentation of Idli/Dosai batter.

By anil on Feb 14, 2016

1kg rice proofing after that how many kg get it

By Ramki Ramakrishnan on Aug 29, 2015

Love the tips for good fermentation. During cooler weather I suggest using a simple digital temperature controller and a 100W light bulb for load to control the oven at a constant 86F to 90F. Amazon sells Inkbird controller for around $16.

By Lily on Jul 20, 2015

Idli batter needs 1:4 and the lid has to have a hole to get air through while keeping for fermentation...Keep them under light until fermentation completes for the available quantity

By Balaji on Jul 5, 2015

I've been told putting it next to the water boiler helps, or in an oven with just the light on should help (wrapping it with a rug to retain heat). I too live in the UK, the number of funny stories i have on fermenting is endless. i find buying batter more easier most of the time... Enjoy.

By karuna on Oct 1, 2014

Hi, I am trying to make idli batter but it's not fermenting at all. I use ratio 1: 3. Please help me. Myself n my love idlis. I live in UK. Waiting for your reply.