Caramelized Onions
Peer reviewed by UK recipe editorsAuthored by UK recipe editorsOriginally published 16 Jan 2026
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This classic caramelised onions recipe is a staple of British home cooking, transforming humble yellow onions into a rich, sweet, and versatile ingredient. By cooking the onions slowly over a gentle flame, the natural sugars break down to create a deep savoury flavour that works beautifully as a base for soups or as a gourmet topping for grilled meats.
As a low-fat accompaniment, these onions are ideal for meal prep and can be stored in the fridge for up to a week. Whether you prefer them lightly golden for a French onion soup or dark and jammy for a homemade burger, this method ensures a consistent and delicious result every time. Pair them with a sharp Cheddar or a crusty baguette for the ultimate comfort food experience.
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Ingredients for Caramelized Onions
2 large yellow onions, peeled (about 450g )
2 tablespoons unsalted butter
Kosher salt
Low-sodium chicken broth or water (for pan
optional)
How to make Caramelized Onions
Halve both onions through root end. Using the tip of your knife, cut a V-shaped notch around root to remove it (this will ensure that all slices separate when you cut the onion).
Place 1 onion half on your cutting board so root end is facing you, then thinly slice onion lengthwise, starting at one side and working all the way to the other (so your knife runs through the root halfway through, not starting or ending at the root end). You’re going for slices that are 1/4"–1/8" thick.
Repeat same slicing procedure for remaining onion halves. It’s a lot of onion! But it will cook down quite a bit, so it’s best to start with a large quantity.
Heat 2 tablespoons butter in a large saucepan over medium until melted and sizzling. You can use a skillet to cook the onions, but a pan with high sides will keep the onions from flipping out onto your stove. Using a pan that also has a wide base gives water room to evaporate, allowing the onions to caramelize rather than steam.
Instead of dumping in all of the onions at once, which would fill the pot and make it hard to stir (which would then cause the ones on the bottom to cook faster), start by adding just a couple of large handfuls to the pot. Cook, stirring, until onions are soft and starting to turn translucent, 1–2 minutes. Stir in a few more handfuls of onion and repeat cooking and stirring process until you’ve added all the onions. Season with a pinch of salt.
Reduce heat to medium-low and continue to cook onions, stirring every few minutes to prevent them from sticking and coloring too much in any one place, until blonde-coloured, 15–20 minutes. This is the point of doneness for French onion soup! If you feel like onions are getting too brown around the edges or they’re sticking, reduce your heat a bit.
If you’re going for onions that are both softer and more caramelized (say for a patty melt or onion dip), keep cooking, stirring on the regular, until onions are unmistakably golden brown, another 15–20 minutes. Because most of the water has cooked off at this point, there might be some bare spots where the pot could start to burn. If this happens, stir in a splash of broth or water. The liquid will dissolve the cooked-on bits, which the onions will re-absorb.
For extra-dark onions, the kind that make a great burger topping, cook until they start to almost blacken around the edges and go slightly crisp, another 10–15 minutes. This requires constant attention so they don’t burn. No one said caramelized onions were quick!
Let onions cool in the saucepan, then use or transfer to an airtight container and chill. They will keep up to 1 week.
Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.
Article history
The information on this page is peer reviewed by qualified clinicians.
16 Jan 2026 | Originally published
Authored by:
UK recipe editors
Peer reviewed by
UK recipe editors

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