FOR THE POOLISH:

• In a large bowl, whisk together ½ cup (120 grams) lukewarm water and a pinch of yeast. Add flours, and stir thoroughly until smooth and no dry bits of flour remain. Cover bowl loosely, and let stand at room temperature overnight. Reserve remaining yeast in an airtight container, and refrigerate until ready to use.

FOR THE DOUGH:

• In the bowl of a stand mixer fitted with the dough hook attachment, whisk together 1 cup (240 grams) lukewarm water and remaining yeast; add poolish. Add flours, salt, and orange zest, and beat at low speed for 4 minutes. (Dough will come together; it will not be smooth but should not tear when pulled gently.)
• Lightly spray a large bowl with cooking spray. Place dough in bowl. Cover and let rise in a warm, draft-free place (75°F/24°C) for 30 minutes. 
• Using wet hands, fold dough in bowl by grabbing underside of dough, stretch it up, and fold it to center of dough. Do this 4 times around bowl. Add nuts and dried fruit to dough; using wet hands, squeeze nuts and fruit into dough until evenly distributed. Cover and let rise in a warm, draft-free place (75°F/24°C) for 30 minutes, repeating folding dough in bowl. Cover and let rise until smooth, soft, and doubled in size, about 30 minutes more. 
• Line a proofing basket or a medium bowl with a linen dusted with flour. Turn out dough onto a lightly floured surface. Using your fingertips, gently press dough into a disk (about 1 inch thick). Grab bottom edge, and gently stretch and fold bottom third over center third. Stretch right side out, and fold right third over center; repeat with left side. Finish by folding top third over previous folds. Roll loaf away from you to seam side down, and using both hands, cup dough, and pull it toward you to seal. Rotate dough 90 degrees, and pull until a tight smooth boule forms. Make sure to remove any white chocolate, cranberries or pistachios that have poked through to the outside of the boule. Place boule in prepared basket or bowl. Cover and let rise in a warm, draft-free place (75°F/24°C) until dough is puffed and jiggles when basket or bowl is gently shaken, 45 minutes to 1 hour.
• When dough has about 20 minutes left to rise, preheat oven to 450°F (230°C). Place a Dutch oven in oven to preheat.
• Turn out boule onto a piece of parchment paper lightly dusted with flour. Using a lame or razor blade, score top of loaf. Carefully remove Dutch oven, and using parchment to help, place boule with parchment into hot Dutch oven. Cover with lid, and place in oven. 
• Immediately reduce oven temperature to 400°F (204°C). Bake for 40 minutes. Remove lid, and bake until bread is golden and an instant-read thermometer inserted in center registers 205°F (96°C) to 210°F (99°C), 5-7 minutes more. Immediately remove from Dutch oven, and let cool completely on a wire rack.