Roast potatoes can come out of the oven crispy and golden with no pale patches if sprayed with a simple kitchen staple: vinegar. The technique was shared by Barry Lewis, a home cook who conducts food experiments, after he tried it on his own roast potatoes.
Why Vinegar Works
Potatoes naturally contain a lot of water, which turns into steam during roasting. If the skin stays wet, the potatoes can end up colourless and mushy. Vinegar contains acetic acid, which reacts with pectin, a natural substance that helps potatoes maintain their structure. This makes it less likely the potatoes will fall apart, and the acidity can help define the crust during the final cooking stage, giving a crunchier skin.
Lewis said: “About halfway through cooking, I took them out, gave them a light spray of vinegar, turned them, and put them back in. I did this twice in total. What surprised me was that they didn’t taste of vinegar at all. Instead, they developed a slightly better crust and just a touch more depth in flavour.”
How to Make Crispier Roast Potatoes
To try the method at home, you will need one kilogram of Maris Piper potatoes, three tablespoons of vegetable oil, duck fat or goose fat, two teaspoons of white or malt vinegar, and salt.
The type of oil or fat used is also important. Most common cooking oils have a low smoke point, meaning they cannot reach high enough temperatures without turning smoky and burning. Vegetable oil, duck fat, or goose fat can withstand the high temperatures needed to roast potatoes so they crisp up. Using a low-smoke oil, such as olive oil, may make potatoes more likely to turn out soggy.
Step-by-Step Method
Preheat the oven to 220C (or 200C fan). Peel the potatoes and cut them into even chunks roughly five centimetres in size. Place the chunks into a pot of cold salted water, bring to a boil, then reduce to a simmer and cook for eight to 10 minutes.
Once tender, drain the potatoes in a colander and leave them to steam-dry for about five minutes. Letting potatoes rest is important; otherwise, steam becomes trapped, keeping them soft in the oven and turning them mushy. Gently shake the potatoes in the colander afterwards to roughen them, creating more edges for a better crust.
While the potatoes rest, pour the oil or fat onto a baking tray and place the empty tray in the oven for five minutes to heat up. Carefully remove the hot tray, place the potatoes on it in a single layer, and return to the oven. Cook for 25 to 30 minutes.
Once the potatoes start to brown, gently pour the vinegar over them, just enough to coat rather than soak. Turn them over and cook for 10 more minutes until golden. Flip them again, spray the other side with vinegar, and cook for 10 to 20 more minutes. The total cooking time should be around 50 to 60 minutes, and the potatoes should come out with a deep golden, crackling skin.
