The base recipe makes a slightly sour, doughy, and waxy bread with a pretty open crumb and truly amazing candied crust. I adjust the flour composition, leavening time, the wetness of the dough, starter condition, and shaping technique based on what I am looking for. The variations you can produce with a few simple adjustments is amazing.
For a more sour loaf: Feed the starter in the fridge for a few days instead of at room temp. The organisms in the starter that produce sour acids out perform the more neutral bugs at lower temps. Also, a longer, slower rise produces a more developed yeast character in the final bread, so letting it rise for two days in the fridge rather than for half a day at room temp will yield a much stronger flavor contribution from the yeast.
For a chewy, open crumb: Use a higher percentage of high-gluten flour combined with a long rise. I find that King Arthur's Bread flour is so high in protein that it yields a super airy and waxy bread without any kneading. Just let the yeast develop the gluten and give it plenty of time to get nice and airy.
For a softer, nuttier bread use more whole wheat flour. I find that whole wheat flour in the starter mellow the flavor out a bit, too. The bugs seem to really like the extra nutrients because they start fermenting much more vigorously. This means a shorter rise time, and less strong flavors.
For pizza, make a wetter-than-usual dough and a big, healthy dose of recently fed starter, a quick rise, and add some oil. This makes for a nice neutral taste and a softer texture.
Some other guidelines and outlines of terms, basic concepts, and techniques can be found here.
So the basic recipe: Rustic Country Bread
Tap Water 75%
Fresh Leaven 20% *Give it a big feeding about 8 hrs before you mix the dough*
White Flour 90% *My favorite is Whole Foods Organic All Purpose Flour. Regular All Purpose Flour is a little too soft, and bread flour is a little too hard.*
Whole Wheat Flour 10%
Salt 2% *If you can find smoked salt, it really adds a neat depth.*
Dissolve the leaven in the water. Add the rest of the flour and mix by hand just enough to get it all wet, then let it just sit for at least 30 min.
Add the salt and turn by hand just enough to be sure that everything is evenly distributed. Let the dough sit in a covered container for at least 4 hours at room temp, folding the dough over its self in the container every 20 min or so (less often and more gently after the first three hours). *If you find that the bread is too soft, consider spending a few minutes slapping the dough to help develop the gluten more*
Remove from container and divide into as many hunks as suits your desired number, shape, and size loafs. Gently shape each hunk into a rough ball and let sit for 15 min or so so that he gluten can fully relax for the shaping. *For pizza, just stretch it out, no need for a second rise. Top it add nauseum, and bake in the hottest possible oven (seriously, 3 min at 900F is ideal).*
To shape the balls gently flatten the dough and fold it into thirds like a letter and in half again the opposite way, then pinch the seam together. Let 'em rise for two to four hours covered and coated in rice flour (to prevent sticking) seam side up.
When it is all fat and puffy its time to bake it. Have the oven ready at 500, flip 'em onto the pan seam side down, cut some big scores in the tops so that they have room to grow (and it looks pretty) and cover with the lid. Leave it covered for the first 20 min, then turn the oven down to 450 and take the cover off. Bake for another 20 min, turning reg so that you don't get uneven burning. Dun.