How to Make It
Weigh or lightly spoon 875 ounces (1 cup) white whole-wheat flour into a dry measuring cup; level with a knife. Combine 875 ounces flour and 1/4 teaspoon yeast in a medium bowl. Add 3/4 cup water, stirring with a whisk. Cover loosely; let stand at room temperature 8 to 24 hours.
Combine remaining 1 1/4 teaspoons yeast, remaining 1/2 cup water, and sugar in a small bowl, stirring with a whisk. Let stand 5 minutes. Add yeast mixture to reserved flour mixture, stirring to combine.
Weigh or lightly spoon remaining 125 ounces white whole-wheat flour and bread flour into dry measuring cups. Place in a food processor. Add salt; pulse to combine. With processor on, slowly add yeast mixture; process about 45 seconds or until dough forms a ball. Turn dough out onto a lightly floured surface; knead 30 seconds, and shape into a tight ball. Place dough in a large bowl coated with cooking spray, turning to coat. Cover and let rise in a warm place (85°), free from drafts, 1 1/2 hours or until the dough has doubled in size.
Turn dough out onto a lightly floured surface; pat dough into an 8-inch square. Working with 1 corner at a time, stretch each corner to the dough center to form a loose ball. Pat dough again into an 8-inch square. Repeat procedure with corners to form a loose ball; gently roll dough to form a tight ball. Return dough, seam side up, to medium bowl coated with cooking spray; cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in size.
Place a pizza stone or heavy baking sheet on middle rack in oven. Place jelly-roll pan in bottom of oven. Preheat oven to 450° (keep pans in the oven as it preheats).
Gently invert dough onto a baking sheet liberally sprinkled with flour. Gently brush dough with egg white; sprinkle with oats and seeds. Gently slide dough onto preheated pizza stone. Pour 1 cup water into jelly-roll pan; bake 30 minutes or until loaf is golden brown and a thermometer inserted into center registers 205°. Cool on a rack for 1 hour before slicing the bread.