The South Indian dish uttapam not only tempts our taste senses but also has some intriguing culinary science behind it. The batter's fermenting process is where the magic happens. Rice and urad dal ferment because of the presence of naturally occurring bacteria. The batter's complex carbs, proteins, and lipids are broken down in this way, making them easier to digest. Fermentation not only improves the uttapam's flavour and texture, but it also makes more of the food's beneficial elements available to the body. As lactic acid is created during fermentation, it imparts a nice taste to the food. The science behind uttapam's preparation demonstrates the remarkable versatility of fermentation as a means of producing a healthy and appetising dish.
Author of the book, Masala Lab: The Science of Indian Cooking, Krish Ashok on his Instagram shares Food Science Lessons from Dr Vaigai Puyal masterclass for making oothappam. He says, the humor in his style of delivery and the waiter's reaction has made us all ignore the gastronomic genius in his actual explanation. Let's explore that. Most people assume that the use of water on a cast iron griddle is to wash off bits of previously cooked dosa. That's not the only reason. When you cook on cast iron repeatedly with oil, it polymerizes and forms a thin layer that is nonstick. This is what's called seasoning cast iron. So, to make sure that those don't stick, you must not wash the surface too rigorously with rough materials like steel wool. That's why he (Vagai) recommends a coconut twig-based broomstick. it will not remove the tin non-stick layer of polymerized fat.
The other science reason for sprinkling water in between making dosas is that cast iron does not transfer heat evenly. Some parts of the surface will be hotter than other parts. This is why sometimes homemade dosas often have uneven browning, some dark spots and some white spots. So, using water and a broom not only washes but also evens out the temperature across the surface. Liquids always transfer heat more evenly because of convection than solids. When you make a dosa, the goal is to use the smallest amount of batter to make a dosa with the largest surface area. This will ensure the thinnest and therefore the crispiest dosa because more surface area exposed to heat equals more evaporation of water equals more crispness. But uthappam is trickier, if you make the surface area larger, then you don't give enough time for the toppings to cook because the bottom will brown too fast if it's too small then. The thickness of the batter will be too much and the insides will not cook, so neither too big nor too small.
How you cut vegetables determines their final texture after you cook. The smaller you cut, the greater the total surface area, so the quicker they cook and the more crisp they become with onions and carrots cutting them really small. Also ensures that the milliard reaction happens more efficiently. And note carefully how he (vagai)recommends not putting the carrots from a low height, but from a higher height. Again, that is Michelin star level advice. If you want even distribution of something you need to drop it from a higher height. Important for salt, podi, onions and carrots.
Rule zero of delicious food is used as much fat as you can. Fats transport flavor because the outer circumference is larger. He recommends 10 ladles of ghee on the outside and six on the inside. Ghee will also ensure even heat transfer. But it transfers heat evenly because of the convention. And as water evaporates, you need all the key to ensure that the milliard browning reaction happens evenly across the. Again, that means more milliard reaction, more deliciousness.