Onions earn their place in so many dishes because they bridge savoury and sweet. Raw, they are crisp, peppery and bright; cooked, they mellow into something buttery. That shapeshifting character makes onions versatile in a variety of dishes, including stews, curries, pies, gravy, burgers, and tart fillings. It’s no secret that cooking onions is the best way to improve their flavour, and caramelising is arguably the most flavoursome method.
The deeper transformation comes from two processes. First, onions sweat and soften as moisture escapes from them. Then, with patience, browning reactions unlock those jammy, toffee-like notes. Simply Recipes creator Elise Bauer puts it plainly: “Onions are naturally sweet, and as caramel comes from the simple cooking of sugar when you slowly cook onions over an extended period of time, the natural sugars in the onions caramelise, making the result intensely and wonderfully flavorful.” But moderate heat and patience must be combined with another step to make them even more delicious, says Elise.
Deglazing is the finishing touch that intensifies savouriness and turns stickiness into a glossy glaze.
The Simple Recipes creator suggests that this can be done by adding a little balsamic vinegar or wine to the pan just before the onions are finished cooking. It helps to deglaze the pan and bring some additional flavour to the onions.
It is not necessary for delicious caramelised onions, but it will make them even tastier.
The Simply Recipes founder suggests a flexible palette: chicken or vegetable stock, bourbon, Marsala wine, Port wine, light beer (because dark beer might add too much flavour), apple juice, or cider.
Add a modest splash, let it bubble, and scrape with a wooden spoon to dissolve all the browned goodness back into the onions.
The principal benefit of deglazing is that it stops the intense sugars and proteins stuck to the pan from scorching and becoming bitter.
Caramelised onions recipe
Ingredients
- Several medium or large onions, yellow, white, or red
- Extra virgin olive oil
- Butter, optional
- Kosher salt
- Sugar, optional
- Balsamic vinegar (or other liquid to deglaze)
Method
Peel and slice the onions to your preferred thickness. Then, heat the olive oil in a wide, thick-bottomed sauté pan to ensure good contact with the onions.
Spread about one teaspoon of olive oil, or a mixture of olive oil and butter if desired, at the bottom of the pan.
Heat the pan over medium-high heat. When the oil appears shimmery, add the onion slices and stir to coat. Ensure the onions are evenly distributed in the pan and stir often.
Depending on your stove’s strength, you may need to adjust the heat to medium or medium-low to prevent the onions from burning or drying.
After 10 minutes, sprinkle some salt over the onions, and optionally, add a little sugar to enhance caramelisation.
Add a small amount of water to the pan to stop the onions from drying out.
Cook the onions for 30 minutes to an hour, stirring every few minutes. When they begin to stick to the pan, let them do so and brown slightly, then stir to prevent burning.
Elise at Simple Recipes says that the trick is to leave them alone and stop stirring long enough to brown the onions.
After the first 20 to 30 minutes, you may want to lower the stove temperature a little and add a little more oil if you find the onions are close to burning.
Use a spatula to scrape up the browned bits from the pan’s bottom as caramelisation happens. As the onions soften, you may need to scrape more often, perhaps every minute rather than a few minutes.
Continue cooking and scraping until the onions turn a deep brown. Then, add your choice of liquid to deglaze the pan and boost the flavour.
Store the mixture in an airtight container in the refrigerator for several days.