How To Caramelize Onions
PREP TIME5 minutes
COOK TIME40 minutes to 45 minutes
INGREDIENTS
- 2 to 4 large yellow onions
- 2 tablespoons unsalted butter, olive oil, or a mix
- 1/4 cup white or red wine, vegetable or chicken stock, balsamic vinegar, or water
- 1/2 teaspoon kosher salt
- 1/8 teaspoon baking soda (optional)
- 1 tablespoon water (optional)
EQUIPMENT
- Large skillet
- Wooden spoon
- Bowl
- Measuring spoons
INSTRUCTIONS
Slice the onions. Trim the tip and root from 2 to 4 yellow onions. Halve each onion from root to stem, then remove the skins. Thinly slice each half from root to stem.
Heat the fat. Melt 2 tablespoons unsalted butter in a large skillet over medium heat, or heat 2 tablespoons olive oil until shimmering.
Add the onions. Add all the onions to the skillet and stir them gently to coat with the fat.
Caramelize the onions. Cook the onions, checking on them every 5 minutes. Stir the onions and scrape up any fond that forms on the bottom of the skillet with a wooden spoon. Exact cooking times will vary with the number of onions you're cooking, their liquid and sugar content, and their age.
• Around 10 Minutes: Onions will start to soften and turn translucent in spots. They will release a lot of liquid into the pan.
• Around 20 Minutes: Onions will be very soft and starting to break down. Some onions will start to show spots of caramelization and you may see some fond starting to build up in the pan. They will also start to smellcaramelized. Adjust the heat if the onions seem to be cooking too quickly or you notice any burnt spots.
• Around 30 Minutes: Onions should be light blonde in color and starting to become jammy. More fond is starting to build up, but it should still be fairly easy to scrape it up with the evaporating liquid from the onions.
• Around 40 Minutes: Onions are golden and starting to smell very caramelized. Taste one — if you like the way they taste, you can stop now! For even deeper caramelized flavor, continue cooking.Deglaze the pan and salt the onions. When your onions have finished cooking, pour in 1/4 cup water, wine, or broth. As the liquid bubbles, scrape up the fond and stir it into the onions. Use additional liquid as necessary to scrape up all the fond. Season with 1/2 teaspoon kosher salt.
Add baking soda, if desired. Mix 1/8 teaspoon baking soda into 1 tablespoon water until dissolved, then add to the onions. Cook, stirring constantly, until the water evaporates, about 30 seconds.
RECIPE NOTES
Storage: Refrigerate in an airtight container up to 1 week or freeze for up to 3 months.
How We’ve Re-tested This Recipe
In September 2019, we pitted six of the most popular caramelized onion methods against one another to determine the best. The winner was a technique heralded by America’s Test Kitchen, which begins by steaming the onions, covered, over high heat. The onions are then cooked uncovered over medium-high heat until caramelized, at which point a baking soda solution is stirred in.
Given this newfound method, we felt it was time to look at our own caramelized onion technique to see how it stacked up. I got out my sharpest chef’s knife, slid onion goggles over my eyes, and started slicing.
Despite attending to both the timing and doneness indicators, the onions made using America’s Test Kitchen’s method burned, imparting a bitter taste. Ultimately, we found that Kitchn’s technique of cooking the sliced onions over moderate heat gave more consistent results. As a result of this testing, we did decide to clarify some steps. Toward the end of cooking as moisture from the onions evaporates, the onion’s sugars caramelize more quickly. We’ve added instructions to increase the frequency of stirring as the onions brown and form fond on the bottom of the pan. As a nod to the winning skills battle contender, we’ve also added the optional step to stir in a bit of baking soda in the end to intensify the color and sweetness of the onions.
— Patty, June 2020
