The thirtieth Bread Baker's Apprentice challenge (from the book by the same name authored by Peter Reinhart) is Basic Sourdough Bread, and is found on pages 233-235.
The bread dough takes a seed culture which we made, taking the better part of a week but was not viable, so I tossed it all out and started over again. At the end of the next week, it was still slow, earning the name Slo Mo, but it was good enough to make the first of the sourdough breads.
Ingredient list for seed culture: rye, bread flour, water. After the seed culture is made, the barm step is next, ingredients for that are bread flour, water, seed culture. Finally we get to the Basic Sourdough Bread recipe and the ingredients for that are barm, bread flour, water, bread flour, salt, and water.
The process for making the bread is pretty much the same as any bread, the main difference being the sour taste from the starter. Since you don't use all of the barm, it stays behind in the refrigerator to be fed and used for other loaves of sourdough bread. The longer it lives, the deeper the sourdough flavor, and I could taste the difference already between the first loaves I made and the additional ones at the end of the week.
The dough recipe made two 1-1/2 pound loaves. Matt ate most all of it...one one day and the other another day. I think I had one slice and Mark had a couple, but Matt really loved this bread. So much so, that I made another two loaves at the end of the week as Margaret was baking them and I decided to just join in since I knew Matt would love to see more of this bread. Delicious. Really really good.
You can visit the main group and marvel the breads. I'm getting there...Slow and Steady. Our next challenge: New York Deli Rye, found on pages 236-238.