Growing up there was always bread at home. Either from a local bakery or later my grandmother baking it daily. I grew up loving it and appreciate it. Later in life I was introduced to more complicated flavours of break, namely sourdough. Sourdough, according to Andrew Whitley, means a dough fermented with naturally occurring yeasts and lactobacilli and without industrially manufactured yeast. Chances are you know all that though and you are here because you want to start baking your own Sourdough bread. Your motivations may vary but among its benefits is much better taste, no need to go and buy yeast, better for you gut (since it's introducing good bacteria) and it's better for your digestion as well.
To make this delicious bread though you need the starter or starter culture. This starter is nothing else but natural occurring wild yeasts and lactic acid bacteria (lactobacilli), that are present anyway in every wheat or rye flour. By adding warm water in that flour we are creating the ideal conditions for that bacteria to grow. They feed on sugars that they convert from flour carbohydrates through the action of enzymes. Another benefit is also the fact that lactobacilli create natural occuring antibiotic compounds to neutralize potentially harmful bacteria.
The importance of flours in our starter
What flour you choose (Rye vs Wheat) to feed your starter will define its identity and its feeding schedule. More importantly though you'll find that different starters have subtly different taste profiles. In the end of the day the bacteria culture that you end up is slightly different and therefore gives a different taste. You can read more here.
Anecdotaly I find that a wheat starter is slightly more actively fermenting and as a result you have to be a lot more regiment with its feeding schedule. A rye starter is a lot more forgiving and it's the starter of my choice. That poor culture has been left starving for days and still managed to successfully bounce back. It has also provide me with amazing loaves of bread. It's my good friend and I generally prefer rye starters. So my recipe is going to be for a rye starter.
Rye sourdough starter recipe
Before you start, you will need a plastic container with a lid but not one that closes air tight. The reason is that a starter is a fermentation and as a result it can created gases that if you trap they can create high pressure and make your air tight container pop. So instead use a container with a lid that closes but it isn't air tight. Here's the recipe. Note that every time you add flour and water you need to stir it well with a spoon for the entire mix to become uniform.
Day 1: 25gr rye flour + 50gr lukewarm water (ideally at 40 degrees Celsius. Or use your finger to be lukewarm)
Day 2: 75gr starter from day 1 + 25gr rye flour + 50gr lukewarm water
Day 3: 150gr starter from day 2 + 25gr rye flour + 50gr lukewarm water
Day 4: 225gr starter from day 3 + 25gr rye flour + 50gr lukewarm water
That completes the preparation stage. At this point you should see you starter being a bit bubbly, smelling a bit fruity and if you taste it with your finger (it's safe) it should have a slightly acidic flavour. If by day 4 you don't see the bubbling don't despair, different temperature in the room can slow down or speed up your starter. Give it a couple of days. Also if you see some gray liquid on top your starter don't be scared, it's fine. Just stir it in with the rest of the flour and water.
After day 4 you get to a normal feeding schedule. That means that from now on you need to throw away some percent of your starter (or donate it to friends or make other recipes) and add flour and water as normal to feed it. You can keep the same percentages as above (25gr flour, 50gr water) and you'll have a fairly liquid starter. I prefer my starter to be more solid as I can observe better its lifecycle. So personally from day 5 onwards i feed it 50g of rye flour and 50gr of lukewarm water. Keep your young starter out of the fridge and keep feeding it for a few more days.
My starter felt really alive after day 6. I baked my first loaf on day 10. At this point it's still very young and results on the bread rise may vary. Don't despair, keep feeding it and it will be stronger.
Maintaining a starter
Once your starter is alive and working you don't need to keep it on your counter and feed it every day, that's expensive. You can put your starter in the fridge and take it out the day before you want to bake. So if you want to bake on Sunday take the starter out of the fridge on Saturday, feed it and then you are good to go. If you are not baking very often remember to feed it once a week at least, even in the fridge.
If you are going away for a long time you have some options. You can leave it in the fridge for up to two weeks, even three. It will be in a sorry state once you are back (gray liquid on top, smelling super acidic) but don't be alarmed. Throw away most of it, keep 20%, feed it your normal schedule and it should bounce back in a few days.
If you are going away for much longer then you can freeze it. Then a few days before you decide to bake take it out and start feeding it again as above. It should be ready to go. Generally speaking they are very resilient. But don't forger it. Keep feeding it.
Throwing away starter
During feeds you need to throw away some starter. I know that people have ethical issue with this as it is wasteful. There are many recipes out there if you search for "sourdough starter leftover recipes". This article has some very interesting ones, my favourite being the pancakes. They are OUT OF THIS WORLD.
A very interesting idea, by my friend Kiriakos, is to keep all the leftover starter in another container and use it as a percentage of the flour that a recipe requires. He made some Greek koulouri (Akis Petretzikis calls it Greek bagel) for example, where the recipe was calling for 350g all purpose flour and 150g hard flour. He used 300gr of his leftover starter instead of the all purpose and it came out great. You can find the full recipe for it here, by Akis Petretzikis.
Finally I need to share my other favourite recipe, Pizza. This is a bit more elaborate but the result won't disappoint you.