Add the water, sourdough starter, olive oil, honey, and sea salt to the bowl of a stand mixer. Stir briefly to combine.
With the mixer running on low speed, gradually add the hard red wheat flour and khorasan flour. Mix until all of the flour is incorporated and no dry spots remain.
Cover the bowl and let the dough rest for 10 to 30 minutes. This gives the freshly milled flour time to fully absorb the liquid.
Add the yeast and knead on medium speed for 10 to 12 minutes, or until the dough looks smooth and elastic. The dough should be smooth, elastic, and tacky but not overly wet.
Transfer the dough to a lightly oiled bowl. Cover and let rise for about 3 hours, or until doubled in size.
Lightly grease two loaf pans or line them with parchment paper.
Lightly dampen your countertop, hands, and bench scraper. Turn the dough out onto the counter and divide it evenly into two portions.
Gently press one portion into a rectangle about 10 x 7 inches.
Fold the bottom edge up toward the center. Fold the right side inward, then fold the left side inward.
Fold the top right corner diagonally toward the center, then repeat with the top left corner to create tension in the dough.
Starting at the top, tightly roll the dough toward yourself into a loaf shape. Gently pull the loaf toward yourself with your hands or a bench scraper to create additional surface tension.
Place the shaped loaf into a prepared 9x4 loaf pan and repeat with the remaining dough.
Cover the pans with a towel and let rise for about 60 minutes, or until the dough is domed and beginning to rise above the top edge of the pans.
Bake at 375°F (190°C) for 35 minutes, or until golden brown.
Remove the loaves from the pans and transfer them to a wire rack. Let cool completely before slicing.