Scenario: You've spent hours making a delicious stew and for some reason the potatoes are still firm, even after an hour of simmering away. Why? Why aren't they cooking? Well, it's time to look at your ingredients. Do you have anything acidic in the stew? Wine? Vinegar? Lemon? Maybe some tomatoes? The thing is, when you cook potatoes (or dry beans) in an acidic environment, they will never get soft. You'll always be left with, at the very least, a bit of an al dente effect, if not a full-on crunchy texture. Carrots work this way, too, altough a crunchy carrot is less of a concern than a crunchy potato. So remember, if you're adding acid to a cooking liquid, make sure your potatoes are cooked through first. Or, cook the potatoes separately and add them in at the end. Photography: Annabelle Waugh