In a large bowl, stir together ⅔ cup water, ¼ cup plus 2 tbsp. all-purpose flour, and yeast until a smooth paste forms; cover with plastic wrap, and let sit for 24 hours. Repeat this process for the next eight days, adding ⅓ cup each water and flour the second and third days and ¾ cup the remaining days, to make the starter (which you can keep alive, in the fridge, by adding the same amounts once weekly.)
On the 10th day, place ¼ cup starter in a bowl and stir in ⅓ cup water, ¾ cup bread flour, and ¼ cup apple cider to create sourdough culture (Figure A); let sit for 12–24 hours, until ready to bake.
Uncover culture and add remaining ⅔ cup water, 3 ¼ cups bread flour, ¾ cup cider, along with cranberries and salt (Figure B). Stir until dough forms (Figure C); let dough sit to let flour hydrate, about 20 minutes. Transfer dough to a floured surface, and knead, using a bench scraper to help remove dough from surface, until smooth and elastic, about 10 minutes. Transfer to a greased bowl; cover with plastic wrap, and place in a cold oven. Let rest until slightly inflated, about 1 hour. Transfer dough to a floured surface and flatten slightly. Fold top and bottom edges toward middle. Return dough, seam side down, to bowl (Figure D); cover. Let sit until doubled in size, about 3 hours.
Repeat folding procedure, and place dough, seam side down, into a greased 8″ x 5″ x 2 ½″ loaf pan, cover with plastic again, and return to oven. Let sit until dough reaches top of the loaf pan, about 3 hours. One hour before baking, place a cast–iron skillet on bottom rack of oven; position another rack above skillet; place a baking stone on top of it. Heat oven to 475°.
Using a razor, slash top of loaf at a 30° angle in four spots. Place loaf on baking stone; place ice in skillet. Bake until brown, about 50 minutes; let cool before serving.