Sourdough Boule

To make the soaker: Put the wheat flakes or oats in a heatproof bowl, and pour the boiling water over them, stirring to combine. Let cool to lukewarm before using., To make the dough: In a large mixing bowl, or the bucket of a bread machine, combine the fed sourdough starter and 3/4 cup of the water, mixing until smooth., Weigh your flour; or measure it by gently spooning it into a cup, then sweeping off any excess. Add the remaining dough ingredients plus the soaker, and mix and knead — by hand, mixer, or bread machine — until you've made a soft dough, adding additional water as needed., Cover the dough in the bowl, and let it rise until it's almost doubled, about 1 to 1 1/2 hours., Turn the dough out onto a lightly greased work surface and gently fold it over a few times to deflate it., Shape the dough into a large round. Grease a Dutch oven or baking crock, and place the dough into it., Cover the crock, and let the loaf rise until it's very puffy, about 1 1/2 to 2 hours., Just before baking, brush or spray the loaf with water, and sprinkle with seeds. Use a lame or a very sharp knife to make several slashes across the top of the loaf, in the shape of a pound sign., Place the covered crock into a cold oven, set to 450°F, and turn on the oven. Bake the bread for 35 minutes., Uncover and continue baking until the bread is deep golden brown, about 10 additional minutes., Remove the bread from the oven and turn it out of the crock onto a rack to cool.