Do you swoon for sweet, golden, jammy onions? In this tutorial, you’ll learn all about how to make caramelized onions, with step-by-step cooking photos, make-ahead instructions, and recipe ideas for using them.
When you’re looking to add deep, sweet, nutty flavor to a recipe, caramelized onions can be your best friend. I use them so regularly, they could probably carry the badge of their own food group in my kitchen.
If you’re reading this article, chances are you don’t want to make just any caramelized onions, you want to make really good caramelized onions. Euphoric onions. Mic dropping onions. Onions that I may or may not sneak by the forkful when I’m cooking and start feeling noshy. (I admit nothing!)
Onions reaching those heights take time. More specifically: time, patience, and butter. (Contrary to what you might guess, no added sugar.) Here’s everything you need to know for becoming a caramelized onion-maker extraordinaire.
What You’ll You’ll Need
- Large yellow onions (technically, you can caramelize any onion, but I find that classic yellow onions caramelize the best)
- Sharp knife
- Large skillet or heavy-bottomed pot. I prefer stainless steel or cast iron to develop a great fond.
- Wooden spoon
- Butter and neutral oil, such as vegetable, canola, or regular olive (not extra-virgin). The mixture increases the smoking temperature so the butter doesn’t burn.
- Kosher salt
- A splash of liquid to deglaze the pan, such as water, broth/stock, wine, beer, or brandy.
How to Caramelize Onions: Step by Step
Step 1: Peel and Slice the Onions
Start by halving the onion lengthwise (root end to tip). Cut the root out of each half by trimming a “v” shape around the solid white area. Remove and discard the onion peels.
Slice the onion halves lengthwise into 1/4-inch thick wedges. The angle of your knife should follow the curve of the onion slice. Separate the layers. (Photo 01)
Alternately, you can create half moons by first halving the onions lengthwise and then slicing them crosswise. With any slicing style you choose, the most important part is that the onions are uniform in thickness.
Step 2: Sweat the Onions
In a large skillet or heavy-bottomed pot, melt together 1 tablespoon of your chosen neutral oil and 1 tablespoon of unsalted butter until foaming subsides. Add onions and a pinch of kosher salt and stir to coat with the oil and butter. (Photos 02 and 03)
Cook the onions over medium high heat until they begin to soften and release their liquid, about 5-8 minutes (Photo 04).
Step 3: Caramelize Low and Slow
Lower heat to medium-low and cook, stirring often, until onions are soft and golden brown, about 30-40 minutes longer. Deglaze the pan with 1 tablespoon water, broth, wine, beer, or brandy and stir for an additional minute, scraping off the brown bits from the pan. (Photos 05-06)
Make-Ahead and Storage
Caramelized onions are great staple ingredient to make in advance and keep on hand. To refrigerate, simply cool them to room temperature and transfer to an airtight container. Caramelized onions keep well for 3-4 days in the refrigerator.
Want to make a big batch of caramelized onions and freeze them for later? They’ll last for about 3 months when frozen. (Look for signs of freezer burn before using.)
Freezing Tip: I like to measure and portion caramelized onions into silicone ice cube trays and muffin tins. That way, I know if I need 2 tablespoons of onions, I’ll grab an ice cube-sized block. If I need 1/2 cup, I’ll reach for the muffin size. Once they’re frozen, I pop them out and place them in labeled freezer bags for storage.
Top 5 Tips for Making the Best Caramelized Onions
- DON’T slice your onions too thinly (paper-thin onions will burn) and DO aim to make them the same thickness so they cook evenly.
- DO watch the onions carefully toward the end of cooking, stirring frequently, especially if you like a deep caramelization. Onions can easily go from well-browned to burned.
- DON’T forget to deglaze the pan when you’re finished cooking to get all of the great flavor and color of the fond into your onions.
- DON’T rush it! The best caramelized onions are a low and slow process.
- DO customize the onions with flavors that suit the dish where they’ll be used. Topping a burger? Try deglazing with beer. Using the onions to top or stuff chicken breasts? A splash of Madeira wine is delicious. You can also add freshly-chopped herbs, such as thyme, during the last minute of cooking. Or, stir in a splash of balsamic vinegar at the end, to taste, for a great crostini topping.
Ways to Use Caramelized Onions
You can use caramelized onions in so many different dishes. They’re one of my favorite ways to top a burger (especially when there’s blue cheese or gruyere involved), a pan-seared steak, or steak sandwich. We love them in pasta dishes, folded into quiche fillings and frittatas, as a flatbread topping, and in stuffing for chicken breasts.
You can also jazz up your favorite salads with a spoonful of caramelized onions. I particularly like them with peppery baby arugula leaves.
Try These Recipes with Caramelized Onions:
- 2 large yellow onions (about 1 pound)
- 1 tablespoon neutral oil (such as vegetable, canola, or regular olive)
- 1 tablespoon unsalted butter
- 1 tablespoon water, broth, balsamic vinegar, wine, beer, or liquor
- kosher salt
To Slice the Onions
- Halve each onion lengthwise (root end to tip). Cut the root out of each half by trimming a "v" shape around the solid white area. Remove and discard the onion peels.
- Slice the onion halves lengthwise into 1/4-inch thick wedges. The angle of your knife should follow the curve of the onion slice. Separate the layers.
- You can also slice the onions into a half moon shape. Cut the onions in half lengthwise, and then slice them crosswise into 1/4-inch thick slices. Make sure your onions are sliced as uniformly as possible so they caramelize evenly.
- Melt butter and oil over medium-high heat until foaming subsides. Add onions and a pinch of kosher salt and cook until onions begin to soften and release their liquid, about 5 minutes.
- Lower heat and cook, stirring often, until onions are soft and golden brown, about 30-40 minutes longer. Deglaze the pan with 1 tablespoon of your liquid of choice and cook, stirring, for an additional 1-2 minutes, scraping any brown bits from the bottom of the pan.
- Use, as directed, in your recipe. Caramelized onions can be stored, tightly covered, in the refrigerator for 3-4 days, and in the freezer for up to 3 months. (Click here to read about additional storage instructions.)