By Lauren Haughey Potatoes can truly make or break a Sunday roast, with many aiming to strike the perfect balance between a crunchy outer layer and soft interior. But one TikTok chef now claims their secret can take your tatties to a whole new level – and it involves just one surprising ingredient. While your mind may be jumping to unusual herbs and spices, expert Oli Brandon suggests that simply adding a single teaspoon of baking soda to your usual recipe can make an unbelievable difference. Posting to his page (@olibrandon), he explained: “One teaspoon of baking soda and salt into boiling wa…