Ask The Food Lab: On Sizing Shallots and Frying Curry
So many questions to answer, so little space and time! The two I picked this week are ones that often come up in recipe writing and will hopefully be useful to many of you.
As always, if you have questions to ask, send'em along to AskTheFoodLab@seriouseats.com, and please include your Serious Eats user name in your email. All questions will be read, though unfortunately not all can be answered.
"How big is a shallot?"
I have always wanted to know this: when a recipe calls for one shallot, do you think that means a whole one which includes those two separate inner "halves"? These sometimes come together wrapped in their paper. Or just one of those inner "halves?"
Rule of thumb: If a recipe doesn't specify quantities in a precise manner, then you probably shouldn't trust that recipe. That is, if a book or resource can't bother to be precise when writing their recipes, chances are they weren't that precise when testing them either. Look for sources that make it clear what they mean.
On Serious Eats, every new recipe we publish will contain both approximate number of physical ingredients used ("1 large onion" or "3 medium stalks celery"), but we'll also include the volume you should be working with ("2 medium carrots, diced fine, (about 1 1/2 cups)")*
As for shallots in particular, it's difficult to tell whether one shallot is going to split into one, two, three, or even four cloves when you peel it, so when our recipes call for "one medium shallot," it's referring to the entire thing, no matter how many cloves it splits into. We use the following basic equivalencies:
- 1 Large Shallot = 1/2 cup minced or sliced
- 1 Medium Shallots = 1/4 cup minced or sliced
- 1 Small Shallots = 2 tablespoons minced or sliced
And for the record, it's the amount that matters, not the size. If a recipe calls for "1 large shallot, minced (about 1/2 cup)," go ahead and get that half cup of shallots from any combination of sizes you'd like.
"How do I know my curry paste is toasted sufficiently?"
Lots of recipes of eastern origin instruct you to sauté up a mixture of spices "until the oil separates." I'm thinking specifically of Thai curries cooked in coconut milk or Indian masalas sautéed in pureed tomatoes. Is it really an indication that the spices are indeed 'cooked' and it's time to proceed with the recipe?
It may seems like a relatively arbitrary thing to say "until the oil separates," but it's actually a much more precise measure than you may think. To understand why, you have to take a closer look at what's in your pot when you start a curry. We've got:
- Ground or pounded spices, herbs, and aromatics. These are the main component of curry pastes, along with salt. They're what give your food its flavor.
- Water. This can come either from the herbs and aromatics themselves, or from water-based additives like fish sauce or soy sauce.
- Fat. These are generally added, though some vegetables do contain their own fat which make it into the paste. In the case of Thai curries, this often comes directly from coconut milk, which, like regular milk, is an emulsion of fat in water.
In order to maximize the flavor and complexity of a curry, it's important to toast the spices and aromatics at a relatively high temperature—in the 300 to 400°F range. This toasting causes a cascade of chemical reactions which take a few simple flavor compounds and transform them into hundreds of new ones.
But here's the problem: As we just said, curry pastes contain water, and this water acts as a built-in limiter to how hot the paste can get. Water evaporates at 212°F, and until most of the water in a paste is driven off, you'll have a hard time getting that paste hot enough to toast your spices.
Luckily, as your paste cooks and water evaporates, eventually there is so little water left that the fat droplets in the paste come together and coalesce, breaking out of the paste and forming a distinct, oily layer in the bottom of the pan. It's only after this layer forms that your paste can get hot enough to start toasting. And be careful, because once it hits that threshold, it'll very rapidly increase in temperature.
Just how rapidly? Well consider that in order to change one gram of water to steam, it takes 2,257 Joules of energy. In order to raise one gram of oil by 1°F, you need only a single Joule of energy. So with the energy it takes to evaporate a single gram of water, you can raise the temperature of a single gram of the oil that's left behind by over 2,000°F! No wonder it's so easy to burn curry paste!
Got a question for The Food Lab?
Email your questions to AskTheFoodLab@seriouseats.com, and please include your Serious Eats user name in your email. All questions will be read, though unfortunately not all can be answered.
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.