In the sci-fi universe of Frank Herbert’s Dune, it is said that “he who controls the spice, controls the universe”. The corollary for the Indian kitchen is—“(s)he who controls the tadka, controls the cuisine”. If subcontinental food was a voluminous sci-fi novel, the act of heating fat and adding whole spices to it would be the prologue and the epilogue. Every dish in the subcontinent begins and/or ends with tempering, also known as tadka, thalippu, oggarane, etc. Tadka distinguishes Indian food from the rest of the world. If Vladimir Harkonnen, arch-villain in Dune, put a gun to my head and asked me to describe Indian cooking in just one word, I would go with tadka.
We start with fats for a few reasons. First, they don’t chemically react with your food. In fact, fats are broken down into fatty acids only in your intestines. You might wonder how they get there, given that you and the rest of your food are mostly water and fats rather famously don’t mix with water. It turns out that your liver produces bile, which emulsifies fats into something resembling mayonnaise. Second, most spice flavour molecules are more fat-soluble than water-soluble, so to get their flavours into food, they need to be knocked out energetically with heat and dissolved in hot fat. Third, fats stay as liquid at temperatures well above the boiling point of water. In addition to efficiently extracting flavours from spices and preventing their aromas from escaping into the air, they can transfer enough heat to get sugars and amino acids in your ingredients to undergo the Maillard browning reaction, which unlocks even more flavour.
So what fats should you use? Well, for starters, you pick the fat used in a particular regional cuisine. If you are making Chettinadu food, use sesame oil. Kerala food—coconut oil. Punjabi food—ghee, and so on. And once you have picked your choice of fat, consider this—cold-pressed oils tend to have lower smoke points. This is the temperature at which the oil starts to visibly smoke. Unrefined oils have non-fat components that burn at high temperatures. These molecules lend extra-virgin oils their characteristic aroma and taste but they don’t survive the high temperatures required for a good tadka, so please don’t use cold-pressed oils for tadka or deep-frying. Any and all extra flavour from the fat is destroyed at high temperatures.
There are two notable exceptions, though—ghee is just clarified butter, so it has a very high smoke point regardless of how it’s made. Mustard oil is also excellent for high temperature uses regardless of whether it’s cold-pressed or refined.
What temperature should you heat your fat up to? If the tadka is at the start of the cooking process, I recommend 130 degrees Celsius, and if it’s for the finishing tadka, a higher temperature of 150 degrees Celsius is recommended. The goal of the opening tadka is depth of flavour and the goal of the finishing tadka is to impart a whiff of flavour without it getting too intense, so the higher temperature destroys most of the intense flavours by design. The belief that oil has to be hot enough before you add your spices is a myth. You can add the spices and then bring the oil to smoking hot temperature and it will not make any difference. The reason our grandmothers used that heuristic was to check if the oil was too hot, not to check if it was hot enough.
Spices like garlic, fenugreek or curry leaves can end up burning if the oil is too hot. The characteristic crackling of mustard or cumin, which typically go in first, can give a seasoned cook a quick sense of how hot the oil is. On a side note, crackling mustard seeds (which contain a baby mustard embryo) in mustard oil feels like the sort of thing an arch plant villain might do while laughing maniacally. But we digress.
The sequencing of ingredients in a tadka is determined by the thickness of the spice’s coating or the amount of moisture in a fresh spice. Mustard, cumin and pepper are all relatively burn-proof, while more delicate spices can burn quickly. Garlic is added after onion because the latter has more moisture. In general, whole spices are preferred because powdered spices will likely burn and add bitter flavours to your dish.
It’s not just spices that are added to tadka—you can also add textural elements like dals and nuts. When they are roasted in oil, they impart added flavour from the browning and add a crunchy element to your dish.
The choice of fat and spices used defines a particular Indian sub-cuisine. You can take any dish and simply swap the tadka with another kind of fat and mix of spices and that will transpose that dish to another cuisine. No matter what the rest of the dish contains, if you start with sesame oil, curry leaves, shallots, garlic and fennel, it will taste like Chettinadu food.
In the world of Dune, the spice melange unlocks prescience and enables interstellar travel. Tadka grabs blandness by the scruff of the neck and shoves it through a portal to deliciousness. I will take the latter anytime.
Krish Ashok is the author of Masala Lab: The Science Of Indian Cooking.
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