Unusual ingredient Nigella uses to make her roast potatoes crispy

Nigella Lawson once shared the very unusual ingredient she uses to make the perfect roast potatoes.

The 62-year-old chef shared her recipe for the crispiest potatoes on Instagram last Christmas, and all you need is salt and pepper, olive oil, and apple cider vinegar.

Lawson revealed she steams her potatoes for 30 minutes before popping them in the oven to increase crispiness.

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"While steaming then roasting potatoes may seem rather a fandango, one bite of these will convince you that it's utterly worth it; besides, it's not as if you have to do anything while they either steam or roast," she wrote.

"Go slowly when adding the salt and vinegar, tasting as you go, as I like these to have the wincing hit of salt and vinegar crisps, and you may prefer a lighter hand with the sprinkling."

At the time, Instagram users praised Lawson for her unsuspected use of apple cider vinegar.

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"This is the KEY to ensuring your spuds are perfectly fluffy. Queen Nigella strikes again," one wrote.

Another wrote, "I've been riffing off this for months and making different versions and they're SO good. Thank you for introducing them to me."