I'm much impressed with the seriousness of this forum, and the keen interest in coming to grips with this elusive phenomenon that we call sourdough. My experience with sourdough bread baking started out with impressive defeats, most of them due to not understanding basic facts. The reason I kept going has much to do with the grace of my wife and my two children who always ate what I hauled out of the oven. – In the meantime I've learned many things about baking, and I would like to pass on what I feel could help others to steer a more direct course to success in the art we all love. And I have already found out, of course, that there are lots of people out there who can teach me a thing or two as well! So, I'm looking forward to interesting exchanges to come.
I live in Germany, where I was born and raised, but I have also spent several years in the US and in Canada. So my English is working okay, I guess, though I must say that the specialized terminology used in discussions on baking in the US is a bit of a challenge for me. It took me a while to realize that "proofing/proving" can mean ANY type of rising (so Wikipedia tells me), - while in Germany we distinguish (using different terms respectively) between the rising of the starter + flour and water, the rising of the sourdough, and the rising of the final dough. I realize, of course, that any kind of rising is "proof" of the vitality of the dough, so I'll add the term to my vocabulary! We also never use an indication equivalent to "hydration". --- well, SOURDOUGH is a theme that tolerates all kinds of approaches.
Let me start off with a sure and simple way to make a sourdough starter. Since I mostly bake rye bread I use rye for the process, whole grains ground finely; but you may just as well use wheat. The difference is mainly that a rye starter can be stored for a longer period of time in the fridge.
Here is what you need:
Mix the ingredients thoroughly, and put the mix in a big enough transparent glass jar so the starter can double its volume or more, and cover the content with a thin layer of flour – that will help you determine when the process is finished. Through the glass you will be able to observe what's happening, and when the flour on top of the dough turns into a torn up convex surface with lots of dark cracks in it, you will be done. The jar should be placed somewhere where you can maintain a temperature of 30 – 35 degrees Celsius for a couple of days (see hints down below). Contrary to common belief lactic acid bacteria need no oxygen to proliferate, so you should put a tight lid on your jar. You will add NOTHING to this mixture during the maturing of the starter, but you need to stir it (thoroughly again) once a day. After two to three days you will see lots of bubbles and your starter is complete when you see bubbles all over AND the cracked surface has become rounded (it's actually real sourdough already and you could bake a small loaf of bread with it, - adding flour, water, and salt, of course), - Be sure to smell your new darling, it will have a very fruity flavour and taste. My guess is: Due to the lack of oxygen there will be no Escherichia coli generating the vomiting smell, or worse.
It is a very convenient procedure with one hitch: it's necessary to maintain these 30+ degrees Celsius (~ 90-100 degrees Fahrenheit) fairly constantly,
Here are some methods that for the most part do not require much technical gear, except a decent thermometer that you can read well.