It's sourdough

I mixed a lump of dough for a loaf of no knead bread a couple months ago, I didn't have time to bake and left it in the fridge.  Soon enough I forgot about it, and when I opened the lid a few days later, it smelled a bit sour and it had a layer of grayish liquid on the top.  Toss it out?  Nah, stir it up and add some water and flour, leave it on the counter and see how it turns out.  A day or two later, the thin soupy mixture had come back to life, making bubbles.

I took a cup out to which I added flour, water and salt.  Then I fed the mixture with some water and flour. A day later I baked the dough, yielding a modest loaf, but quite sour.

Days later, the starter looked more like a wet dough.  For the next two loaves, I took 250 gm of starter, added 200 gm water, 310 gm white flour, 40 gm whole wheat flour and 1.5 tsp salt.  I fed the starter with 1/4 cup water and 1/4-1/2 cup flour, but the starter seemed to need more when I mixed for the fourth and fifth loaves.  time was about 14 hours. baked better loaves of bread, with regard to loaf height for 800 gm of flour/water (the amount for a "traditional" no knead bread).

In conclusion, the process by which one gets a sourdough starter can include using the yeast from a one pound package of SAF Instant yeast, of which I still have at least an ounce after four or more years.  Maybe the wild yeasts are superior, and maybe you could say you got yeasts resident to your part of the world, but sour is sour and the bread is great, especially in combination with the long ferment times.  ITrader Joes' sourdough breads never tasted this good!