100 Techniques

Technique #48: How to Quickly Caramelize Onions

With just two unexpected ingredients, you can caramelize onions in half the time.

Published Sept. 14, 2023.

This is Technique #48 from our 100 Techniques Every Home Cook Can Master.

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Given heat and time, onions transform from pungent, crunchy, and raw to deeply flavored, meltingly tender, and caramelized. The classic approach involves very low heat—and upward of 1 1⁄4 hours.

Shortcut efforts usually rely on cranking up the heat and typically produce wan flavor and watery texture lurking beneath a deceptively browned exterior. But here’s a trick that will allow you to make them in half an hour without sacrificing results: 

Add water.

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Secret #1: Water is Your Friend

You might think that water is an obstacle to be eliminated. It’s true that moisture is the enemy of browning, but the first part of the onion-cooking process is about softening, not browning. Surrounding the onions with steam at the outset heats them more quickly than the cooking surface of the skillet alone would. 

So adding water and covering the skillet causes the raw onions to wilt faster and more evenly as the water turns to steam. Then, uncover the skillet and begin a process of pressing the softened onions into the bottom and sides of the skillet for maximum contact—and maximum browning. 

Press, let them sit for about 30 seconds, and stir, and then repeat this process for 15 to 20 minutes.

As the softened onions caramelize, they release water, sugars, and proteins. The water evaporates, concentrating flavor. Some of the sugars undergo caramelization, in which their molecules recombine into hundreds of new flavor, color, and aroma compounds, and the amino acids in the proteins react with some of the sugars to undergo Maillard browning, producing an equally diverse array of flavors and aromas.

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Secret #2: Finish with Baking Soda

In addition to water, we have another secret ingredient: baking soda. We often turn to it to speed browning, since it creates a high-pH environment, which allows caramelization to occur more readily. Baking soda is also handy for softening vegetables because altering the pH helps weaken their cell structure. 

Further, baking soda speeds up the conversion of natural flavorless compounds called inulin into the simple sugar fructose, so that the fructose can then interact with the amino acids to produce flavor. So while many caramelized onion recipes call for adding honey or sugar, our onions are deliciously sweet without any assistance.

Watch Cook's Illustrated's Lan Lam demonstrate how to quickly caramelize onions.

Step by Step: How to Caramelize Onions Quickly

Now that you've learned the science behind the "why," it's time for you to give quick caramelized onions a try. Just follow these simple steps.

Step 1: Slice Onions Through the Root

Slice onions through root ends (slicing with direction of fibers preserves structure and prevents too much breakdown during cooking process).

Step 2: High Heat, Add Water and Oil, Cover

Start onions over high heat in skillet with water and oil, bring water to boil, cover skillet, and cook until water has evaporated and onions start to sizzle.

Step 3: Uncover, Lower Heat, and Cook

Lower heat and use rubber spatula to press softened onions into sides and bottom of skillet. Cook without stirring for 30 seconds to let browning occur, then stir, scraping fond from skillet.

Step 4: Cook Until Well Browned

Repeat pressing, cooking, and stirring process until onions are well browned and slightly sticky.

Step 5: Finish with Baking Soda and Water

Combine baking soda and water in small bowl. Stir mixture into onions and cook, stirring, until solution has evaporated and onions have darkened.

Recipes That Use This Technique

Want to put your newfound knowledge of caramelized onions to use? Try it with these recipes.


Caramelized Onions

The key to quicker caramelized onions is the ingredient we least expected: water.
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Caramelized Onion Dip

The savory-sweet flavor of caramelized onions gets showcased in this quick and easy dip.
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Caramelized Onion, Tomato, and Goat Cheese Tart

Sweet caramelized onions, creamy goat cheese and bright, fruity tomatoes create a light but flavor-packed tart.
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Pasta with Caramelized Onions, Pecorino Romano, and Black Pepper

We accented caramelized onion's sweetness by blooming coarsely ground black pepper in butter for this comforting pasta dish.
Get the Recipe

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