A little before the SARS-CoV-2 virus decided to shut the entire planet down for a year, I made a trip to Udaipur in Rajasthan, notionally to soak in the magnificence of Mewari royal architecture overlooking a beautiful lake, but actually to stuff my face with dal baati and churma till my insides threatened wholesale rebellion. After I had stuffed myself with this ghee-soaked delicacy a few times, my wife gently reminded me that any further consumption of this would result in legal proceedings.
We then took a walk down the city roads to sample the local street food, and while I expected to find a mix of chaat, Indo-Chinese and Rajasthani fare, I was rather surprised to find a large number of idli and dosa carts. The conventional wisdom that it’s hard to find good south Indian food in small towns up north seemed to have been upended by the practical economic advantages of selling idli and dosa. It takes a lot of labour to sell something like, say, aloo paratha from a cart compared to idli and dosa.
Once you have the fermented batter, you can steam a hundred idlis in one shot, and that’s not the end of that. Leftover idlis can then be turned into idli chaat, idli manchurian and the like. Culinary innovation accompanying rapid economic growth is generally seen in the streets, not as much in our homes, where hidebound ideas of tradition and authenticity tend to prevail.
So, let’s delve into the science of this fluffy steamed dish. If I told you that idli is a gluten-free version of sourdough bread, you might reach for the pitchforks, but hear me out. Idli is made from a lacto-fermented batter made of urad dal and rice, and a family of bacteria and yeast very similar to the ones that ferment wheat into a sourdough starter get to work. If you have ever baked sourdough bread, you will realise that the starter literally smells like idli batter.
Depending on which part of India you live in, if you use rice and urad dal, and grind the rice more coarsely than the dal, you get idli batter. If the rice is finely ground and the batter is slightly more watery, you get dosa batter. If you replace the urad dal with chana dal, you get dhokla batter, and if you skip the rice altogether, you get khaman batter. Fermented grains and legumes have a long history in the subcontinent, and the process improves the nutrition of the finished dish in addition to leavening it, meaning the trapping of bubbles of carbon dioxide generated by the bacteria that results in a lighter and airier product when steamed.
The ratio of rice to dal in the batter determines the texture and nutrition of the idli. Since rice is cheaper than dal, you will find that street-food idli tends to use a 4:1 ratio, while it’s not uncommon for middle-class folk to use a 3:1 ratio that results in more protein in the final product. A particularly premium version of this dish, called the Kanchipuram idli, uses a 1:1 ratio. It’s the rice that determines texture and mouthfeel, while it’s the legume that mostly determines nutritional value. The kind of rice used to make idli tends to be parboiled rice, more nutritious than raw white rice, which is mostly carbohydrates and little else. Although you can use any parboiled rice, idli rice, which is a specific variety of slightly high-amylose rice, will give you softer idlis.
If you forget to soak rice and dal ahead of time, you can add water heated to 80 degrees Celsius to unsoaked rice and dal, and then grind them to a batter. This process will kill all the natural bacteria and yeast present in the grains, so you will need an inoculum. You can use a little bit of fermented batter from an earlier batch or a bit of yogurt.
A common set of doubts that people tend to have: How long should I soak the rice and dal? Typically, at least five hours. Oversoaking can result in a pasty-textured idli. You should also soak the rice and dal separately so that you can grind the rice more coarsely than the dal. It’s also a common practice to add a teaspoon of fenugreek (methi) seeds during the grinding process because the seeds tend to harbour lots of useful bacteria on their surface, and it serves as an insurance policy in case the bacteria in the urad dal fails to deliver the goods.
Interestingly, and it will come as a shock to purists, you can switch the urad dal to any other legume to make idli. Soybeans make for a fantastic-tasting idli while also packing way more protein than the urad dal version. You can also use chickpeas, moong dal or rajma as the legume. Even the rice can be swapped with millets to produce slightly healthier versions of idlis, although a 75-25 mixture of millets and rice makes for a better-tasting idli. And for side dishes, don’t stop at sambar and chutney. Some of the best side dishes for idlis are mutton and chicken curries, exceedingly common in Tamil Nadu and Kerala. The fluffy airiness is perfect for soaking in gravies. The experience of biting into the idli and releasing the gravy juices is distinctly superior than having meat gravies with steamed rice.
And if your idlis turn out slightly dense, don’t worry. Take a leaf out of the innovative street-food vendors in Udaipur and heat a wok to a blazing high temperature. Sauté some ginger, garlic and chillies, throw in pieces of your disappointing idlis and let them crisp. Then add a bit of soy sauce to finish your Indo-Chinese chilli idli, and judging by the reception this dish got in Udaipur, you won’t be disappointed.
Krish Ashok is the author of Masala Lab: The Science Of Indian Cooking. @krishashok