what is the best recipe for the SOUREST sourdough on the planet? Something that smells like old cheddar cheese as an example?
I use a sponge, and let that sit for 24-48 hours until it has some great smell. Then make the dough and leave it in the fridge for a few days to proof. You won't be disappointed ;)
You ought to take a look at the lesson "Squeeze more sour from your sourdough" on this site.
I've posted a note about my experience with the BBA Poilane-Style recipe.
In general, the advice seems to be two or more long, cold (refrigerated) fermentations for a really sour dough.
NOTE - link was wrong, now corrected.
The other day I tried http://www.thefreshloaf.com/node/257 the recipe with lemon juice. Now, I am German and raised on sourdough, but that was a bit over the top for me.
Maybe you would enjoy it.
I made my first SOOOOOOOOOOOOOUUUUUUUUUUUUUURRR sourdough only a few weeks ago. I was trying to alter a recipe to achieve a more 'ciabatta style' loaf. I made a very wet dough and let it proof for 7 hours instead of my intended 5 - 6hrs. What i ended up with was a round flat italian bread style loaf with amazing, beautful holes of structure but a sooouuuuuurrrr taste. I was so pleased with the appearance, and the initial piece I tried had a wonderful, complex flavour - especially given I had used a mongrel starter (different mixed flours) then some wholemeal, lots of wholemeal spelt and 1/3 white flour to copmplete the dough.
I added enough water to create a very wet, sticky dough that was just about unworkable and barely sustained shape because it was so wet.
After the initial tasting, which was very interesting, and at the time I felt would set the groundwork for future loave of this kind, I started consuming more and more slices to form a sold opinion of my appraoch. After half an hour I was left with a strong vinegar taste at the back of my throat which lasted quite unpleasantly for the entire day. Like I had swilled a glass of red wine vinegar, mistaking it for wine.
So while the sweetness of the spelt grain played around with my senses and the tip of my tongue, the acid from overwet, over-timed dough conditions continued to punish me for a very long time to come.
How to make a dough more sour? Increase water content and warmth to increase The activity of the bacterial component of your sourdough colony and extend the proof time to allow them to most fulfill the task.
Note: strangely, the gluten in the dough held up to this abuse and kept it's end of the bargain.
I've only been making sourdough for about 6 months, so it's still a bit hit and miss for me as well. I'm slightly surprised that you want more sour after the rather unpleasant experiences you had with what you made. However the perceived wisdom is that a long COLD fermentation is the way to go. Proof the dough at room temperature (3-6 hours depending) till it has risen to the size you want, then cover and refrigerate over night. Bake it the next day.
NOTE, the link I posted above to the lesson on this site was wrong, I've corrected it.