From cheese to vinegar, throughout the centuries we have deliberately let - and even encouraged - food to go sour to enhance its flavour. Now, sour foods have never been more fashionable, with the spotlight falling on foodstuffs as disparate as Belgian sour beer and Korean kimchi. But what is it that makes sourness such an enticing, complex element of the eating experience? And what are the best ways to harness sour flavours in your own kitchen?

Sour offers a series of invitations to the modern cook, to learn the life-enhancing skills behind the everyday transformations that hold the key to this most enduring taste. Award-winning food writer Mark Diacono sets out to demystify the sour world, and explore why everyone's extolling the virtues of kombucha and fermenting for their digestive health. By grappling with gooseberries and turning his hand to sourdough, experimenting with ultra-cool shrub cocktails, and making his own yoghurt, kefir and pickles, Mark tells the story of what makes things sour, and offers recipes that maximise the transformative power of this amazing taste. From sumac-roasted duck and kombucha mayonnaise to roasted plums with labneh and cherry sour cream clafoutis, it is time to let a little (or a lot) of sour into your life.