How To Make Caramelised Onions

Properly caramelised onions are the key to so many delicious recipes. You can’t make a good French onion soup without cooking down a mass of onions until they’re brown and sugary. And the same goes for a sausage and sticky onion ragù or caramelised onion linguine. Onions, although quite astringent while raw, are capable of transforming any dish when they’re cooked right. That’s why we wanted to help you out with this guide on how to make caramelised onions. And, yes, before you ask: quick caramelised onions are a thing. But patience is often the secret ingredient.

First things first, you’re going to want to start by slicing your onions as thin as possible. Not only will this give you a silkier, less chunky texture but it’s also a great way to speed up the eventual cooking process. Making sure you’ve got the right pan for the job will also make your life easier. Most decent non-stick frying pans should do the trick but a stainless steel sauté pan will also work nicely.

Generally speaking: the larger the pan, the better. More surface area means that you’re less at risk of overcrowding the pan and coming out with unevenly cooked onions. In a perfect world, you'd want each slice of onion to have adequate space to spread itself out and get a nice even tan.

Neither. Once you’ve sliced your onions and got the perfect pan to hand, you’re going to want to heat that pan on a medium-high heat and add in a good glug of oil. A general rule of thumb when you’re first figuring out how to caramelise onions is to cook more than you think you’ll need. Onions shrink down a lot when cooked, so don’t be scared about using a couple of onions at a time.

Once you’ve added your onions to the pan with the oil, you’re going to want to add a big pinch of salt. This will (a) help the overall flavour of the onions because everyone knows that salt is king, and (b) help draw out the moisture and ensure that the onions take on a good amount of colour. The next thing you’re going to have to do is to be patient. Caramelising onions can be a time-intensive process and it’s difficult to speed it up without ending up with burned onions. You don’t want to move the onions around too much when they're in the pan either. Try to leave them for as long as possible and only turn them once every six minutes or so when you think they need some love.

We've given you some rough estimates but I know what you’re thinking: “how long does it take to actually caramelise onions?” Well, there are no hard or fast rules about it but you’re going to want to cook them for at least half an hour if you want them super caramelised and sweet. A good trick to employ halfway through the cooking process is to add a splash of water. The water will stop the onions from catching and also pick up all those caramelised nubs of flavour (known as the fond) forming on the bottom of your pan. After that, it’s just a test of patience and willpower. Your kitchen is going to smell great.

If you want to know how to speed up caramelising onions so you've got sweet onions in your pan in five minutes flat then I’ve got some bad news for you. Frying your onions gently is – and always will be – the best way to bring out the best of their natural sweetness. The worst thing you can do is crank up the heat and gift yourself a coal-like mass of burnt onions. That being said, there are a few tricks to help speed up the process and gift you some relatively quick caramelised onions.

The tips we gave above about having a large pan and slicing the onion thinly come in very handy. Another way – if you’re properly pushed for time – is to kick up the heat and add water more consistently throughout the cooking process to deglaze your pan. This constant deglazing will help get your onions cooked quicker and the addition of water will stop them from sticking completely to the bottom of the pan. Another great way to quickly caramelise onions is by adding some baking soda to the equation. Yep, it's a bit GCSE Chemistry but baking soda will raise the PH of your onions so that the Maillard reaction (the chemical reaction between amino acids and reducing sugars which gives browned food its distinctive flavour) takes place faster. Don’t use too much, though. Just a pinch will do.