Cutting into a fresh, ripe avocado to reveal the buttery-smooth, green flesh is pure bliss.

However, avocados aren’t without their flaws. Once you cut into an avocado, you’ve exposed it to its worst enemy: oxygen.

Avocado flesh turns brown when opened to the air because of a reactive enzyme, a process otherwise known as oxidation.

Trying to keep a cut half of an avocado ripe is an uphill battle. But there are some preventative measures you can take to protect that beautiful green flesh from turning brown and unappetising.

After trialling out different storage methods, food expert Jerry James Stone has shared the “winning” solution.

He said: “There are many methods out there for keeping cut avocado from going to the dark side.

“While a myriad of methods have been tried and tested. I will tell you, most don’t work well. I put 12 methods to the test and there was a clear winner.”

For its “ease and effectiveness”, Jerry claimed that the onion method is the “clear winner”.

He said: “Stored this way, sliced and diced avocado can keep fresh and green for up to five days.”

Where the other 11 methods involve moisture, which ultimately degrades the avocado, the onion method does not.

The expert instructed: “To keep your cut-up avocado fresh, simply store it in an airtight container along with some chopped-up onion.

“The colour does not matter. Red, yellow, white, or whatever. It just has to be an onion.”

Onions contain sulphur compounds that, when released, slow the oxidation that causes browning.

For those who like onion, they can simply place a slice of it over the top of the avocado, put it in an airtight container, and keep it in the fridge.

However, for those who don’t like onion, simply having it in the same container helps. Jerry noted that the transfer of flavour is “minimal to none”.

When it comes to whole ripe avocados, they are best stored in the fridge to slow down the ripening process. Keep them in the drawer of the fridge and they’ll last between two and three days when stored this way.