Sourdough does everything - leavens the bread, adds a more complex flavour than any other leavening agent, makes the ingredients more accessible to our bodies, and keeps the bread fresher longer, says Lutz Geißler, blogger and author of bread-baking books.

Sure you can buy sourdough in supermarkets, but according to the bread expert, making it yourself is clearly better. "Homemade sourdough is alive, while the one in the supermarket is dead. It has been heated and only serves to add some acidity to the dough," said Geißler.

When you make sourdough yourself, "you have full control and can make it pleasantly mild," he says.

Making sourdough at home is actually quite simple, requiring only flour and water. "Definitely use organic flour," says Sonja Bauer, food blogger and cookbook author.

"Otherwise, pesticides from the outer layers of the grain could be present." She suggests using wholemeal flour, such as rye, wheat or spelt, or a medium-light rye flour.

Consistency should not be too runny

Mix the flour and water. "For rye, it's 50 grams of flour and 50 grams of water," says Geißler of the consistency. "It should be like mortar, so you can still stir it with a spoon, but it shouldn't be liquid."

Making a completely new sourdough takes three to five days in total, he says. "Better a bit longer than too short."

The principle is simple: keep feeding it and otherwise leave it alone. "Place it in a warm spot," Bauer says. The temperature should not drop below 22 degrees Celsius. "Ideally, it should be between 26 and 28 degrees."

Typically, you feed your starter with fresh flour and water every 24 hours for a few days.

"It is important to feed it when it needs food," says Geißler. His tip is to feed it whenever the dough has roughly doubled in volume.

Initially, this may take longer than 24 hours, but later it could happen in 12 or even eight hours. "In the first week, it's important to keep an eye on it," he says.

The good news is that ideally, you only create a sourdough starter "once in your life; after that, the effort is much less."

Two methods for 50-50 feeding

You always feed your sourdough with 50 grams of flour and 50 grams of water. This either increases the amount of sourdough, which is practical if you need a few hundred grams for baking, or, after two or three days, you can remove 25 grams of the starter and feed it with the 50-50 mixture, says Geißler.

Bauer's method, on the other hand, follows a 1:1:1 ratio. After mixing 50 grams each of flour and water, she removes 50 grams of the starter after 24 hours and adds another 50 grams each of flour and water, repeating the process daily.

How often you do this depends on what you plan to do with the dough. For Bauer, it takes five to seven days before she can make a first loaf.

Bubbles and a pleasant smell - signs of success

You can tell that the microorganisms in the sourdough are active by the small bubbles that form after one or two days.

After several days of feeding, a finished sourdough smells pleasant. "If it doesn't smell musty like an old shoe or like nail polish remover, but instead fresh, sour and fruity, then it's ready to use," says Geißler.

At this point, you can either bake directly or, according to Geißler, place 50 to 100 grams in a screw-top jar in the fridge. This is the so-called starter, which can be used to quickly create a bakeable sourdough again.

A sourdough beginner's recipe

For beginners, the bread baker has a simple recipe: 500 grams of sourdough are mixed with 360 grams of flour (e.g. wholemeal rye or light rye flour), 220 grams of warm water and 13 grams of salt.

"The dough should have the consistency of spreadable liver sausage," says Geißler.

Place it in a loaf tin and smooth it with water. Let it rise in a warm place for 2.5 to 3 hours, by which time the dough should have grown to about half its original size.

Then bake the bread at 250 degrees Celsius (top and bottom heat) for one hour. After about 10 minutes, reduce the temperature to 200-210 degrees.

If possible, bake with steam, as this creates a crispy, thin crust. Alternatively, "Cover the loaf with a pot for the first half of the baking time," says Geißler. "I'm a rye fan. For me, a sourdough rye loaf is still the best of all breads."

You may wonder whether sourdough bread needs additional yeast. Not really, the experts say. "The more yeast in the bread, the quicker it goes stale," says Bauer. She adds a maximum of 5 grams of yeast to sourdough bread. "Yeast can give young sourdough a bit of a boost."

To avoid having to create a new sourdough starter each time, you regularly refresh your starter in the fridge.

Ideally, feed it once a week, whether or not you are baking. For simple refreshing, Geißler says add 50 grams each of warm water and flour - preferably the same flour as the starter - to a new jar and stirring in a spoonful of the old starter.

If you want to bake, feed the starter to the required recipe amount, plus a little extra for the 50-100 grams of starter that will go back into the fridge.

For example, if Bauer needs 250 grams of sourdough for a bread dough, she takes 100 grams of starter and adds 100 grams each of water and flour. With this 1:1:1 ratio, a resting time of about four hours is sufficient, and the sourdough is ready to bake.

She puts the rest back in the fridge as refreshed starter.

The quantities are flexible: you can also use just 10 or 25 grams of starter and feed it with, for example, 150 grams each of water and flour. In this case, the dough should rest longer, such as overnight. Some calculations are required.

"Everyone does it a bit differently," Bauer says. Start by baking the same bread repeatedly to gain experience, is her advice.

Making sourdough holiday-proof

Try to avoid freezing sourdough, says Bauer. If you are taking a longer break, or heading on holiday, simply feed your starter with more flour to make it firmer.

Wait an hour and then store it in the coldest place you can, for example, at the very back of the fridge on the glass shelf.