how do I make brade sour?

I read on www.sourdoughhome.com that if you want a more sour sourdough you need to use less sourdough starter.  The reasoning behind this is that the less sourdough you use will mean a longer rise time.  The longer rise time will produce more acid and alcohol that you will be looking for to produce that sour taste.

Thus if you know someone who likes the sourdough to be less sour you thus use more sourdough starter