I tested 5 fats to make the crispiest roast potatoes — this is the winner

Roast potatoes are a British institution, and no roast dinner – including Christmas – is complete without them. Methods of roasting differ from household to household, and while there’s no one set way to cook them, some techniques are definitely better than others.

To find out which cooking hack delivers the best roast potatoes, I put five different methods to the test. Some had incredibly surprising results, while others are not worth your time. There are two fats that came out on top, and you should consider using them for your roast potatoes this Christmas.

Duck fat was the last fat I put to the test. It’s an ingredient usually reserved for special occasion roast dinners, such as Christmas.

This fat is a little more expensive and upmarket than your regular oil. While visually very unappealing, like grainy lumps of mush, the results couldn’t be further from that.

Duck fat works best when trying to cover all over the potatoes, ensuring it’s in every nook and cranny. Although the potatoes may not be the darkest, they display a wonderful golden-caramel coloured shell. I say “shell”, more like a crust.

Each potato was perfectly coated in a noticeable crust that distinguishes the outer shell from the pillowy insides. Texturally, duck fat is the winner, hands down. Whereas if you’re after an extra flavour dimension, I’d add in a little mayo.

In comparison to the mayonnaise and clotted cream potatoes, there aren’t as many greasy, crispy burnt ends to scoop up from the tray to nibble on. The quality of the potatoes definitely makes up for that.

Duck fat is consistent and delivers great results.

Score – 5/5

Reading about the mayo hack penned by Simply Recipe’s Erika Kwee, who claimed mayonnaise is an upgrade, I knew I had to try it. Mayo isn’t a condiment I use in everyday life, but I’d try anything for a good spud.

All you need to do is coat the parboiled potatoes in the mayonnaise before roasting. The recipe called for 20 minutes in the oven at 200C, but in reality, it took around 40 minutes to achieve a golden crisp.

Mayonnaise is a game-changer. Not only did the potatoes have that enviable brown crisp, but the crunch didn’t disappoint.

The mayo achieves its desired goal and it certainly helped with the flavour too. The roast potatoes had this hint of sweetness from the caramelised parts of the skin. Thankfully, the mayo didn’t overwhelm the taste of a classic roast potato.

Honestly, this mayonnaise hack is a game-changer when it comes to roasting potatoes. The logic is right there in front of us. Once you try it, you’ll never go back.

Score – 5/5

After the surprising success of the mayonnaise, another unconventional fat that floated around was clotted cream. Usually reserved for scones and afternoon tea, recipe developer and TikTok creator Madeleine Wilmshurst, better known as @fannychupp, claimed clotted cream has better uses with spuds.

The clotted cream didn’t melt as easily as the mayo had done, but as long as the potatoes were cloaked in its fatty film and resulted in a crisp outside, then it shouldn’t matter. However, not all of the potatoes – no matter how coated they were – seemed to crisp up. 

Some roasties had slightly flabby outsides, not too unlike the spuds school used to serve up for school dinners. Fortunately, there were only a few. 

All of the potatoes were beautifully tender on the inside like fluffy little pillows. However, one slight downside was the flavour of the clotted cream. 

Its sickly sweet flavour was more prevalent than the mayo had been, which is something I should’ve probably expected. When it melts, the clotted cream caramelises, creating a rich, brown butter flavour and a golden, crispy exterior while keeping the inside soft and fluffy.

I was pleasantly surprised by the clotted cream’s success, but I definitely think it would benefit from some additional seasonings to tone down the inevitable sweetness.

Score 4/5

Oil is probably one of the most commonly used fats to cook roast potatoes. However, recipe developer Amy Sheppard argued that you need a blend of vegetable and olive oil to ensure the outer shell is crisp and crunchy.

Heating the oil to a high enough temperature is essential, but even that wasn’t enough to achieve the perfect roast. The mixture of oils, personally, I don’t think outperforms using only one oil.

If anything, I don’t think it makes a difference at all. I can’t quite see the result that was desired.

Despite coating the potatoes liberally in the hot oil and turning them over in the pan, the roast left a lot to be desired. The oil resulted in a very uneven roast, rendering about half of the potatoes a dark yellow rather than golden brown.

If your aim is to achieve a more even crisp and crunch on all of the potatoes, I’d avoid using oil altogether.

Score – 2/5

This was by far the most outlandish cooking hack I’ve read relating to roast potatoes.  Simply Recipes’ Molly Adams borrowed the technique from chef J Kenji Lopez-Alt, whereby baking soda is added to the saucepan of boiling water with the potatoes. 

The idea is that because baking soda is an alkali, adding it to the water for the potatoes creates an alkaline environment that breaks down the potato’s outer edges, releasing starches to form a starchy slurry that crisps up when roasted.

Once the potatoes were boiled, they were already incredibly fluffy without needing to chuff the spuds. This “slurry” coating is what helps the roast potatoes crisp up.

This technique is technically less about the fat, so oil will suffice… if the baking soda actually worked. Baking soda is not the holy grail it was served up to be. 

If anything, the roast potatoes lacked one major element – the roasted part. Although the baking soda worked to make the potatoes fluffed up, much can’t be said for just how crispy and roasted they were. 

Baking soda is not the missing ingredient in your roast potato puzzle, not in the slightest. Baking soda is better left in the cupboard.

Score – 1/5