Easy Sourdough Bread

bread flour (I use King Arthur)

one-17.6 ounce (500 gram) tub plain unsweetened Greek yogurt with active cultures (must say ‘active cultures’, I used 0% Non-Fat Fage)

about 1/2 to 1 cup sour cream (or Greek yogurt, lite versions are okay), or as needed see below step 1

 teaspoon salt, or to taste

scant 1 teaspoon (just slightly less than 1 teaspoon) instant dry yeast (I use Red Star Platinum) for 6 to 12 hours rising (use closer to 1/2 teaspoon yeast if you plan to allow dough to rise for 12-18 hours; see step 4 below)