What You Are Making
Lift the lid of a pot of batter on the morning after grinding and you will know straight away if it worked. A good batter has swollen up the sides of the container, the top is domed and full of tiny holes, and the smell is mildly sour, a little like fresh dough. A bad one sits flat, smells of nothing, or smells wrong. Idli sounds like the easiest dish in the world, since it is only steamed rice and lentil batter, yet it is among the hardest to get right, because nearly everything depends on a fermentation that runs overnight and out of sight, with no way to rescue it once it is underway. When it goes well, idli is soft, faintly tangy and nearly spongy. When it goes badly, it comes out dense, flat and gummy. For that reason this recipe spends as much time on the batter as on the steaming, since the batter decides almost every outcome.
The Dish’s Backstory
In Tamil Nadu and Karnataka, idli is a pillar of what the South calls tiffin, the family of light breakfast and snack dishes, often savory. Where it came from is honestly debated. One camp of historians follows a steamed, fermented rice and lentil cake back over a thousand years within South India itself. Another, which includes K.T. Achaya, points to a possible link with Indonesia, because the earliest written hints of something like idli appear in accounts of trade between South India and Southeast Asia. Neither case is closed, and it is more honest to leave the question open than to pick a side. What can be said with confidence is that idli has been ordinary home cooking and temple food in the South for many centuries, however the method first arrived.
At the Stove, Step by Step
-
Prep
Soak the rice and the dal apart from each other
Rinse the rice, cover it generously with water and leave it 4 to 6 hours. Do the same with the urad dal and fenugreek in a second bowl. They stay separate because the dal wants a long grind to trap air, whereas the rice should stay a little rougher.
-
Prep
Whip the dal until pale and airy
Strain the dal and fenugreek and grind with only the colder water needed to keep the stones or blades moving, scraping the sides down at intervals. The batter should become smooth, pale and clearly full of air, about twice the bulk of the dry dal. That takes longer than expected, usually a quarter of an hour or more in a wet grinder and less in a strong blender, and the trapped air is what makes the finished idli light.
-
Prep
Grind the rice to a coarser paste
Strain the rice and grind it by itself to a paste that still feels faintly grainy. A bit of grit is welcome here, in contrast with the dal, which you want as smooth and airy as it will go.
-
Prep
Mix by hand and leave to ferment
Scrape both batters together and mix with a clean hand, since a machine would beat out the air. Use a roomy container, because the batter may double in volume or more. Put a loose lid on it and let it sit somewhere warm, about 25 to 30°C (77 to 86°F), for 8 to 12 hours, which usually means overnight. In a cool kitchen, stand the container in an oven that has only its light on, or in an Instant Pot set to yogurt, to keep the warmth steady.
-
Prep
Check that the batter has fermented
Good batter has climbed the container, wears a slightly domed top full of bubbles, and smells gently sour and a bit like bread, never harsh or unpleasant. Add the salt only now, folding it through softly so the batter does not collapse.
-
Cook
Steam the idli
Brush the idli plates with a little oil and spoon batter into each cup until it is three-quarters full. Set them over water that is already boiling hard in the steamer or pot, close the lid, and steam for 10 to 12 minutes. A toothpick pushed into one should come out clean, and the top should bounce back under a light touch.
-
Serve
Rest, then unmould with a wet spoon
Once the steam stops, wait 2 to 3 minutes before taking out the idli with a spoon dipped in water. They finish setting while they cool a little and release without sticking after that. Eat them hot with coconut chutney and sambar.
Stand-ins If You Are Short
Three parts rice to one part urad dal is the classic, dependable ratio, though some households go to four to one for a denser idli. Steel-cut idli rava, a coarse parboiled rice, can stand in for whole rice, and since it is partly prepared already it gives first-time fermenters a little more room for error. Fenugreek is optional, yet it helps both taste and fermentation, so add it if you have it.
Dial the Chilli Up or Down
Idli itself carries no spice. Its appeal is its texture and its mild tang, and the heat comes entirely from the chutney and sambar served alongside. Those can be changed freely to taste without affecting the idli.
Where It Goes Wrong
Batter that stays flat is the failure most people meet. It usually traces back to a kitchen that is too chilly, dal that was ground without enough air, or salt added too soon, which can hold fermentation back, and that is why it goes in afterward. Dense idli from batter that did rise point to a rough dal grind, or to stirring the risen batter too hard so the bubbles burst. Idli that refuse to leave their cups were probably under-oiled or pulled out before resting.
Leftovers, Kept and Revived
Keeping: Keep fermented batter in the refrigerator for up to 4 to 5 days. It goes on souring slowly even when cold, so the first day's batter and the fourth day's batter taste different, the older one tangier and thinner. Idli that are already steamed can wait in a sealed box in the fridge for 2 to 3 days.
Reviving: A fresh 3 to 4 minutes in the steamer returns idli to softness. Alternatively, cover them with a damp paper towel in the microwave for a short burst so they do not dry out. Firm, dried-out idli do not recover well without extra moisture.
Handle This Part Carefully
Properly fermented batter is safe, and it is not the same as spoiled batter. The difference lies in smell and look. A pleasant sour, slightly yeasty smell and even bubbling mean fermentation. An off, rotten or alcoholic smell, discoloration or mould means the batter has spoiled and should be thrown away, not cooked. Keep fermenting batter loosely covered, not sealed airtight, which can trap excess gas, and keep it away from contamination. Refrigerate it once it reaches the stage where you want fermentation to stop.
Worth Opening Next
- K.T. Achaya, "Indian Food: A Historical Companion" (Oxford University Press) — on the debated early history and possible Southeast Asian influence on fermented rice-and-lentil cakes.