After decades of filling up on flavourless crap, Britain seems to be regaining its taste for proper bread. The biggest beneficiary is chewy, tangy sourdough, which makes a treat of the simplest sarnie. Tesco – hardly a foodie destination – now sells 100,000 loaves of it every week, with sales up 40% in a year.

Sourdough is the oldest leavened bread; the bubbles that make it rise are created not by the commercial yeast used in the vast majority of bread baking, Saccharomyces cerevisiae, but by naturally occurring yeasts found on flour and in the air. It was probably invented when one of our ancestors left some wet flour in the sun and noticed it starting to froth.

Not only does sourdough taste great; there is some evidence it can be tolerated by many people who have trouble digesting bread produced with commercial yeast.

But not all sourdough is created equal. While purists will tell you it should be made from just flour, water, salt and a “starter” that is in turn made from flour, water and the above-mentioned naturally occuring yeasts, Which? has found that most supermarket sourdoughs are adulterated with anything from yoghurt and vinegar to – and this is the real killer – commercial yeast. Those ingredients aren’t bad for you, unless you have a specific intolerance – but to describe bread made with commercial yeast as sourdough is, not to put too fine a point on it, complete and utter bollocks.

How can you avoid this sourfaux? You can check the ingredients, of course – if the supermarket lists them – or switch to an artisan bakery (and ask about the ingredients there, too). Or, you could just make it yourself. It has a reputation for being tricky, labour-intensive and horribly slow, but again, this is a misconception. All you are doing is replacing one quick-acting, predictable ingredient with another that is less consistent and lazier. Everything takes longer, but on the plus side, that gives the dough more time to build flavour.

If you have ever made bread by hand (loading up a machine doesn’t count), you can make sourdough. You will need to be in the general vicinity of the kitchen for about half a day, but for most of that you will simply be waiting for dough to rise. The breadmaking itself won’t get in the way of any dusting, childcare or drinking in front of the telly that you may have planned. Here is a simple recipe, with instructions on how to make a starter.