Combine first 4 ingredients in a large bowl; let stand 5 minutes. Lightly spoon flour into dry measuring cups; level with a knife. Add 3 cups flour, dill, and 1/2 teaspoon salt to buttermilk mixture. Turn dough out onto a floured surface. Knead until smooth and elastic (about 10 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 45 minutes or until doubled in size. (Press two fingers into dough. If indentation remains, the dough has risen enough.) Punch dough down; cover and let rest for 5 minutes. Divide in half. Working with one portion at a time (cover remaining dough to keep from drying), shape portion into 6 (2-inch-long) ovals on a floured surface. Roll up each portion tightly, starting with a long edge, pressing firmly to eliminate air pockets; pinch seam and ends to seal. Place rolls, seam sides down, on a large baking sheet sprinkled with cornmeal. Repeat with remaining dough portions.
Preheat oven to 375°.
Brush egg white over rolls; sprinkle with 1/2 teaspoon salt. Bake at 375° for 25 minutes or until the rolls are browned on the bottom and sound hollow when tapped. Remove from pan; cool on wire racks.