There is nothing quite like a backofenkartoffeln knusprig roasted potato, crunchy on the outside and soft and fluffy in the middle. Making decent roasted potatoes isn’t difficult, it’s just a matter of cutting up some potato chunks tossing them in salt and oil and then roasting them until golden. But to get those seriously crispy potatoes that you dream of, there is one secret ingredient you need – bicarbonate of soda (aka baking soda). You probably have some lying around in your pantry behind the novelty cookie cutters and the seriously out of date almond essence.

The trick to getting those deliciously crunchy potatoes is adding bicarbonate of soda to the parboiling water. This makes the water alkaline, which breaks down the potato skins a little and helps them crisp up better when they are roasted later. It also helps the potatoes cook more evenly and prevents them from absorbing too much moisture.

Baking Soda Alchemy: How to Cook Potatoes to Perfection

It’s important to add the baking soda carefully as it will fizz a bit, and you don’t want any of it to leak into your food. When you’re parboiling, try and use a high starch potato like a russet or Yukon gold. These types of potatoes have more starch, which helps them get extra crispy – especially when cooked with baking soda.

Once the potatoes are cooked, drain them well and then roughen them up a bit with a fork, just enough to break up some of the surface bits. Then put them in a roasting tray and drizzle with some olive oil. Make sure you don’t overcrowd the trays because they need space to crisp up.