Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Combine the starter, water, and flour in the bowl of your mixer just until smooth. Cover the bowl and let the mixture sit (autolyse) for 1 hour., After an hour, add the salt and yeast, and knead the dough with your mixer's dough hook on medium speed for 5 to 7 minutes. Just before the kneading is done, mix in the figs or cranberries., Stop the mixer and add the walnuts, using a dough scraper to fold them gently into the dough. Cover the bowl again and let the dough rise at room temperature for 40 to 60 minutes., Turn the dough out onto a lightly greased surface (it will be fairly wet and possibly a bit sticky)., Scoop up the edge of the dough with your dough scraper and bring it to the center, pressing down. Give the circle of dough a quarter turn counterclockwise, and repeat three or four more times. You're stretching the dough a bit and rounding it at the same time. For two smaller loaves, divide the dough in half and round each., Flour the banneton(s) you want to use, or a tea towel placed inside a bowl with a shape you find pleasing. Place the rounded dough into the banneton or bowl, bottom side up, cover with plastic wrap, and refrigerate overnight., The next morning, preheat the oven to 450°F with a baking stone in the lower third. Put 1" of water into a small skillet that can go into the oven. Take your breads out of the refrigerator. They may not have risen a lot; that's OK., Bring the water in the skillet to a simmer and place it in the bottom of the oven. Place a piece of parchment on a baker's peel or the back of a baking sheet., Turn the loaves out of their bannetons onto the parchment. Slash the top(s) of the loaves, and slide the bread(s), paper and all, onto the stone in the oven. Spray the inside of the oven generously with water from a spray bottle and set a timer for 5 minutes. Spray once more when the timer goes off, and bake for another 35 minutes, until the center of the loaf reads 200°F when measured with a digital thermometer. Remove from the oven and cool on a rack before slicing.