This forum has been so instructive on ideas and techniques and I have pretty much been a lurker here for over 2 years. I have been obsessed with sourdough for most of this period, however, my own efforts--while pretty good flavor-wise--were not the tangy sourdough i craved from my Bay area days.
Until today.
The stars aligned and even though it is 40% wheat (from a local farm), it is very sour. I still have to work on my shaping and cuts, but I am finally happy with the sour.
What do you consider the reasons for your success? I'm on the same quest, and the best I can do so far is mildly sour.
I keep my 2 year old starter in the refrigerator and usually feed it every 1-2 weeks. This time I took it out Thursday night, let it stand for a couple of hours, fed it, let it sit out until I fed it again Friday night, made my sponge Saturday morning. From there I followed the BBA formula, but replaced 40% of white with wheat and increased hydration slightly. I had to mix and autolyse an additional round to get a windowpane.
1sr rise was about 2 1/2 hours; 2nd was 3 hours. My starter is pretty lively.
I think the key was the starter feedings. I am still learning a lot about the chemistry of bread :)
good luck!