Avocados are a morning favourite, whether you are spreading them on toast or whizzing them into a smoothie, but keeping them fresh can prove challenging. Many of us do not consume a whole avocado at once and then mistakenly store the leftover half in the fridge, which typically leads to it spoiling by the following day.

Thankfully, Attosa, a culinary expert from Thrifty Fun, has disclosed that preserving avocados to maintain their "super fresh" quality is remarkably simple - you simply need to store them alongside chopped onion.

She said: "I've tried all the various methods of keeping my avocados and guacamole fresh, but this is by far the best yet. Keep a piece of cut onion in a container alongside your cut avocado or prepared guacamole and it will stay fresh and bright for several days."

So how do onions prevent avocados from browning?

Avocados deteriorate quickly due to oxidation, which happens when enzymes in the fruit encounter oxygen. When avocado pieces are exposed to air, the flesh begins to degrade rapidly, turning brown and soft.

Onions release small amounts of sulphur-containing gas, which interferes with enzyme activity and slows oxidation, keeping avocados fresher for extended periods.

Onion slices do not affect the taste of an avocado, but rather serve as a simple trick to extend their shelf life by several days or even up to a week.

Here's how you can use onions to keep your avocados fresh:

Simply place your avocado in an airtight container, which will help contain the sulphur gases inside. Then, add a few slices of onion to the same container as your avocado slice.

Choose white or red onions as they have more sulphur than their yellow counterparts, making them more effective at preserving your avocados.

Ensure the avocado and onion slices aren't touching, then pop it in the fridge.

This natural hack helps your avocados stay fresh for longer, allowing you to avoid wasting any unused halves, save a bit of money, and reduce food waste.