Learn how to caramelise onions that are deliciously rich and sweet every time with this easy to follow recipe. 

Caramelised Onions

Though easy to make, caramelised onions do take some time as well. They need to be cooked slowly over a low heat to get the best flavour while not burning them.

As onions are naturally sweet, slowly cooking them for an extended period of time allows the natural sugars to caramelise, resulting in deliciously flavourful onions. 

What Onions to Use?

You can use any onion you have, though brown or red onions tend to work the best. I love using brown onions as they turn a lovely golden colour when caramelised. Red onions tend to be a mix of purple and brown in colour.

Caramelised Onions Notes

• The best caramelised onions are cooked low and slow.
• Use a wide pan instead of a saucepan to give the onions space to lay in a single layer as this helps the water from the onions to evaporate faster.
• Use a sharp knife to cut the onions and don’t cut them too thinly as they may start burning before they caramelise.
•  Add a pinch of salt at the beginning of cooking as it helps draw out the moisture from the onions.
• Add the sugar and vinegar after the onions have been cooking for a little bit and have become soft and are just starting to go a golden colour.
• Butter can be used instead of olive oil, though it does have a tendency to burn the onions more but butter does add more flavour.

Using Caramelised Onions

Caramelised onions can really be used for anything.

• As a side dish
• Use instead of regular onions in dishes that call for cooked onions for additional flavour
• Top steaks, baked chicken or fish with them
• Add to sandwiches and burgers
• Use in tarts, quiches and dips
• Sprinkle on top of pizza
• Add to onion soup

More Onion Recipes

Ingredients for Caramelised Onions

• 3 TBSP Olive Oil, more as needed
• 5 Large Onions, finely sliced
• Pinch Salt, optional
• 1 tsp Brown Sugar, optional
• 1 TBSP Balsamic vinegar, optional

Making Caramelised Onions

Heat a large skillet over medium heat.

Add 2 TBSP of the olive oil.

Finely slice the onions and add to the skillet.

Add the salt if using at the start. If using brown sugar or balsamic vinegar, add after the onions have been cooking for about 10 minutes.

Cook for 20 to 30 minutes, stirring occasionally. Stir only enough to prevent them burning. If you stir too much, they won’t caramelise.

Add additional oil or a little water as needed to prevent burning. Balsamic vinegar can help with stopping the onions from sticking to the pan.

Reduce the heat to low and continue to cook for another 15 to 30 minutes until the onions are caramelised.

To speed up the cooking process, add a small amount of salt, balsamic vinegar and / or brown sugar. However, by adding any of these ingredients, the taste and the texture of the caramelised onions will be altered.

Storing Caramelised Onions

Once cooled, store in an airtight container in the fridge for up to one week.

Caramelised onions can be frozen in a freezer-safe container for up to three months. For portion sizes, freeze in ice cube trays, then pop them out and store in a freezer-safe zip lock bag in the freezer until needed.