In stand mixer bowl, add 1 cup bread flour, cracked wheat, yeast, sugar and salt; mix well. Add to warm water and oil to flour mixture. Add sourdough starter. Using a paddle attachment, blend on low speed for 30 seconds; beat on medium speed for 4 minutes.
Switch to dough hook attachment. Gradually stir in enough remaining flour to make a firm dough. Knead until smooth and elastic, about 5 to 7 minutes.(NOTE: For hand mixing: following above steps, mix ingredients in large mixing bowl using a wooden spoon or dough whisk. Knead on floured surface until smooth and elastic.) Place dough in lightly oiled bowl and turn to grease top. Cover; let rise until indentation remains after poking dough with finger down to second knuckle, about 1 hour.
Turn dough onto lightly floured surface; punch down to remove air bubbles. Divide dough into 8 pieces. On lightly floured surface, roll each piece to a 6x4-inch rectangle. Starting with the longer side, roll up tightly, pressing dough into roll with each turn. Pinch edges and ends to seal. Place on greased cookie sheet. Cover; let rise until doubled.
Preheat oven to 400ºF.
With sharp knife, make a lengthwise slash down the center of each roll. For a crustier crust, brush with cold water. Bake for 20 to 25 minutes or until golden brown. Remove from cookie sheet; cool on wire rack.