“We’re about to run out of cheese!” Catherine Mead exclaims with a mixture of panic and pride as she steps out of the dairy and into the cheese shop on her farm in Cornwall. “It takes us months to make each truckle of Cornish Yarg. And we’re almost out!” Ripened in a coating of hand-foraged stinging nettles, Cornish Yarg is a semi-hard cow’s milk cheese with a distinctively crumbly texture and a creamy, mushroomy taste. Inspired by a rediscovered 17th-century recipe, Mead and her fellow cheesemakers have spent decades redesigning…