Making a sourdough starter is easy and cheap, but it takes a bit of time and patience. However, once your sourdough starter is ready it will keep going for years and the lengthy process does not need to be repeated. The starter will survive in the fridge for several weeks in between baking loaves of bread. Only when it goes black or mouldy it should be disposed of. Sourdough gets better with age – the more often you bake with it, the quicker and better your bread will rise. For the first few loaves a bit of yeast can be added (7 – 10 g) in order to support the sourdough’s strength. Bread made just with sourdough can take longer to rise (sometimes up to several hours). I therefore still add a bit of yeast most of the time (or use a pre-dough, as in my rustic rye bread), to safe time.
Below is a description of how I made my own rye flour sourdough starter, which has been alive now for almost a year and its ‘relatives’ are used by several friends to make their own bread. Sourdough can also be made with wheat or other flours, but rye is the most stable and easiest to make:
Day 1: Mix 100g wholemeal rye flour with 100 ml of lukewarm water in a fairly large bowl (more flour and water will be added in subsequent days). Cover the bowl (do not use cling film, but a plate or a loose-fitting lid) and leave in a warm place (25 degrees or higher are ideal) for 24 hours. It can be difficult to find a place in the house that is warm at all times. I rested the sourdough near the boiler when the heating was on. When the heating was off, I wrapped the bowl in a blanket with a hot water bottle filled with warm water, which did the trick! It is important not to let the sourdough get too hot. More than 40 degrees will kill it!
Day 2: add another handful of wholemeal rye flour and enough warm water to get the consistency of a sponge-cake batter. Stir well, cover and leave in a warm place as above for 24 hours.
Day 3: add a further 100 g of rye flour and 100 ml of water. Mix well and put back into a warm place to rest for 24 hours. By this point the sourdough should start smelling ‘sour’ and will be bubbly and light. If it hasn’t done so at this point, just keep going. The smell of sourdough is not always pleasant and can be quite strong, but this is normal. Only if the sourdough is turning black or has gone mouldy something has gone wrong.
Day 4: finally, feed the sourdough with a further 100g rye flour and 100 ml warm water. Mix well, cover and put back into a warm place for another 24 hours.
Now the sourdough is ready to be used for baking bread. Make sure you keep a few spoons full of the sourdough in a small jar in the fridge (before adding any more ingredients) each time you bake. This is your starter for the next bread.