Need to know how to caramelise onions? Want to use them as a topping to steak or as an ingredient in everything from pizzas to soups? You’ve come to the right place – the recipe for caramelised onions below will show you how to make this delicious onion dish.

How it Works

Onions have a high sugar and water content. By removing much of the water and gently heating the sugar you cause the onions to acquire a denser texture, a concentrated sweetness and a rich brown colour.

When sugar is heated for a period of time it caramelises – if you’ve ever made toffee you’ve seen this process in action – and this is exactly what happens inside onion if it’s heated slowly for long enough.

Caramelised Onions Recipe

Caramelising onions is a simple process, but it demands patience. You should allow around 40 minutes cooking time. Don’t try to hurry your onions or you’ll end up burning the onion sugar rather than caramelising it. Greasy blackened onions might be ok on a truck stop burger, but we’re going for something with a little more class here.


  • Onions. You can use any sort – white, brown or red. They will reduce significantly. If you want, say, a cup of caramelised onions start off with 3 or 4 raw onions.
  • Olive oil.
  • Salt.
  • Sugar.
  • Balsamic vinegar.


  1. Top and tail the onions and remove the skin.
  2. Halve the onions, then slice finely lengthwise. The finer you slice your onions, the more exposed to heat they will be and the quicker the caramelisation process will take place.
  3. Place a good splash of olive oil in a wide, flat bottomed pan. A sauté or frying pan is best as the low sides allow the water in the onions to evaporate more efficiently.
  4. Heat the oil until hot – when the oil starts to shimmer it’s ready, if it’s smoking it’s too hot and you’ll risk burning your onions before they have a chance to caramelise.
  5. Spread your sliced onion evenly over the pan base and stir so that all pieces are coated in oil.
  6. Cook for around 10 minutes on a low heat, stirring occasionally.
  7. Add a couple of pinches of salt. Salt will not only enhance the flavour of the onions but will also help to draw out water and make it easier for the sugar to caramelise.
  8. Add 2 teaspoons of brown sugar. This extra sugar gives the sugar in the onions a boost.
  9. Cook for another 30 minutes. As the onions begin to caramelise they will start to stick to the bottom of the pan. This is all part of the process and is necessary for the onions to acquire a rich brown colour. However, don’t allow the onions to stick for too long as they will burn. Scrape the base of your pan regularly with a wooden spatula or egg-slice.
  10. When the onions are pretty much done add a splash of balsamic vinegar. Balsamic vinegar enhances both the flavour and the colour of the cooked onions. Be careful not to use too much, though, or your onions will be too watery.

Patience Rewarded

If you can refrain from turning up the heat and trying to force the onions to hurry along you’ll be rewarded with a pan of succulent, brown, beautifully glazed caramelised onions. Caramelised onions are great by themselves on crackers or fresh crusty bread, but they can also be used in dips, soups, savoury tarts and pizza.

To learn more about caramelising onions check out this video.

How to Caramelise Onions, 4.8 out of 5 based on 4 ratings


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