Working with the SDI starter. I think my starter is "active" and alright
because I can get it to "boil over" out of a 3/4 full jar. At least I have
assumed my starter is alright.

I have been following the recipe in the booklet I received. I get good
looking bread, good texture, moist, good rise during that process (at least
doubles in 2.5 hours) but it just doesn't taste sour. If I could add sour
to this bread, all my problems would be solved.

I am thinking that I need to extend the time during the sponge creation
process. Maybe wait 18 hours before feeding the sponge again (instead of 12
hours) and then wait another 18 hours before mixing the sponge up and
baking. But this is only a guess?

Ideas as to what I might be doing wrong?

I am in Oklahoma and getting SF Sourdough is not a viable option to me. The
stuff the bakery sells that they call sourdough is a joke.

Thanks,
Greg