Sourdough Boule - cooking recipe

Ingredients

1 cup sourdough starter
1 1/4 cups warm water
1 1/2 teaspoons active dry yeast
3 1/2 cups bread flour or 3 1/2 cups whole wheat bread flour
1 teaspoon kosher salt
semolina flour (for finishing)

Preparation

In the bowl of a stand mixer fitted with the dough hook attachment, combine starter with warm water. Beat at medium speed until combined (about 3 minutes). Add remaining ingredients, beating at medium speed until a soft dough forms. (If the dough appears too dry and crumbly, add more water, 1 tablespoon at a time.) The dough should come together as one mass and should appear shaggy and feel sticky.
Spray a large bowl with cooking spray. Place dough in bowl. Cover and let stand in a warm, draft-free place (75\u00b0) for 1 to 2 hours, or until doubled in size.
Turn risen dough out onto a lightly oiled surface and deflate it to remove excess gas and air.
Pull the four corners of the dough into the center, pinching with your fingertips to create a seal. Flip the dough over and begin to tighten the round by cupping your palms around the dough while rotating it.
Line a bowl (approximately 6 to 8 inches in diameter) with a clean kitchen towel, dusted generously with flour. Place the loaf, seam-side up, in the bowl. Cover and proof in a warm, draft-free place (75\u00b0) for 1 to 2 hours, or until doubled in size.
Preheat the oven to 450. Turn the dough out into a cast-iron vessel with a lid, such as a Dutch oven. Dust the boule with semolina flour and score, using a sharp knife (or a lame) to make 3 or 4, 1/4-inch-deep cuts across the top.
Cover and bake for 35 minutes. Increase the temperature to 475, remove the lid, and continue baking for 10-15 minutes, until loaf is deeply browned. Turn out onto a rack and let cool completely before slicing.