A t a recent tasting, I got chatting to a winemaker from Australia’s Clare Valley as I bravely made my way through his wares: a ripe, leathery shiraz and a deep, dark cabernet sauvignon that put me in mind of blackcurrant bushes. These were serious wines – and good value, too. A generation ago, such gutsy New World reds were all the rage, but now, lamented the winemaker, gen Z was more interested in lighter, cooler-climate wines, lower on the alcohol and brighter on the palate. He had two theories on this. One was vanity: no one on Instagram or TikTok wants to drink a red wine that stains their teeth, which is bad news for producers of high-tannin wines such as malbec and cabernet. And, two: it’s also to do with the changing western diet. Aussie shiraz is the archetypal sausage-on-the-barbie wine; Argentinian malbec is a steakhouse cliché; and, in France, malbec is mainly grown around Cahors in the south-west, land of heavy cassoulets and fat-tastic maigrets de canard .…