This won’t take a moment. Here at the Potwell Inn we make kefir most days and using locally produced organic cows milk it costs about £1.30 a litre and takes 24 hours, although you can leave it longer it gets a bit sharper. We got the grains from our son who got them in turn from a dedicated fermenter friend. With a bit of effort almost anyone could find a source of grains – like the ones in the first photo – which are also called a SCOBY (symbiotic culture of bacteria and yeast). It’s not the same as yoghurt. In keeping with our commitment to no-faff cooking (and no-dig gardening) we never take its temperature, just shove it on the back of the stove when we top it up, so let’s say it stays at about 20C all day and then that night it goes into the fridge. During the day it may well separate and look like “gone off” milk and if that offends you give it a shake. When it goes into the fridge it thickens up overnight and at breakfast time we strain it in a chinoise – but any sieve will do – and then top the grains up with milk straight from the fridge. I quite like drinking it straight, I like the sharp slightly fizzy taste, but you can whzz it up as a smoothie with fruit or spinach or whatever. As the grains get more plentiful you can give the excess to a friend. Good eating!