Combine starter, water and salt in a mixing bowl. Stir together with a wooden spoon. Add flour, 1 cup at a time until it all comes together. Cover with wrap and let rest for 1 hour in a warm place. Oil your hands well, stretch the dough and fold in thirds. Stretch and fold again. Cover and let rest in a warm place for an hour more. Repeat the stretching/resting process 3 times in total. After the last stretch, let the dough rest 1 more hour. Grease a cookie sheet. Shape dough into a round or oblong loaf. Cover and let rise in a warm spot for 2 hours. Bake at 350° for 25-30 minutes, until when you tap on the bottom of your loaf it sounds hollow. Cool on rack.