Although heavy on theory, getting sourdough going is surprisingly low-tech in practice. All it really needs is for you to leave flour and water lying around to fester. If you keep adding a bit more flour and water every day, you can easily end up with a viable ‘starter’ or ‘leaven’ – a bubbling source of yeast cells lively enough to make bread within about five or six days. Once you’ve got it going, you keep feeding it with fresh flour and water every three days or so, or you can give it a strategic boost a day or so in advance of making a new loaf.

Man discovered this simple process thousands of years ago and has been making use of it ever since. Today, we’ve managed to make cobbling together a leaven a pretty complicated business: there seem to be as many different methods as there are books about bread-making.

Some writers swear by flour and water alone. Others indulge in a little sneaky baiting of the mixture, leaving things in it that will attract more rapid yeast growth – such as yoghurt and dried fruit. Some people stick to a rye starter which does, admittedly, seem to be the easiest to get going and keep alive. Others branch out into leavens made with other flours. Some get very particular about the conditions, the container and the temperature, others uppity about the water (tap water is frowned upon, although I’ve never found it a problem). Conveniently for most of us, it is also said that you should avoid over-zealous cleaning in the kitchen as this runs the risk of killing off your bacteria.

Although I’ve got starters going by a number of different methods, the one I successfully make most of my bread from is straight from Dan Lepard’s The Handmade Loaf. It has a small amount of rye flour in it, but it’s basically a wheat flour starter and used to make wheat-based bread.

He starts off with 2 tsp rye flour, 2 tsp strong white flour and 50g of water, with 2 tsp currants or raisins and 2 tsp live low-fat yoghurt. You mix all of that up in a covered plastic container and leave in a warm-ish place for 24 hours. The next day, you add 2 more tsp of each of the flours and another 50g water. On day 3, you double the quantities and leave again. On day 4, just when it’s probably starting to look good, you counter-intuitively chuck away three-quarters of it. Add 100g water to what you’ve got left, stir well and then strain the whole lot, removing the manky dried fruit and the flour goo, leaving only the liquid. Add 125g strong white flour to this, stir again and leave another 24 hours.

By day 5, the whole thing should smell pretty ripe and acidic. Again, chuck away three-quarters of it and add 100g water and 125g strong white flour. In another 24 hours, you have a starter you can use to make bread. The rule of thumb after this is to keep on repeating day 5 by adding flour and water – a process known as ‘refreshment’. The ideal proportions seem to be around about 1 part existing starter, 1 part water, 1.25 parts flour.

If you’re canny, you’ll develop a routine whereby you only end up refreshing the starter immediately after taking out the right amount to make a loaf of bread. That way, you won’t have to throw any away. So if, for example, you have around 300g of starter and your recipe asks you to use 200g of it, you’ll end up with about 100g left in the pot, which becomes just over 300g when you next add flour and water, and you’re back to where you started. If you’ve had a break from making a loaf, you’ll probably have to throw some away when you do your next refreshment. Or, you can slow down the whole process by putting it in the fridge, in which case you might only need to refresh the mixture every 7-10 days. If you need to make more than two loaves in a week, you might need to do some forward-planning and adjust the quantities so that you have more ‘left-over’ starter and you add proportionately more flour and water when you refresh it.

It all sounds complicated and I’ve put in quantities as a guide but, as with all of this, you don’t have to be too precious and you can get away with a lot of haphazard management. All you really need to know is that a ‘hit’ of flour and water should get a sluggish starter going again. Even if you follow all the instructions to the letter, sometimes there just won’t be much happening. It’s really all about being sensitive to what a lively and a dormant starter looks and smells like. Never be afraid to throw a lot away and do try to resist building up a big lifeless stock of goo.