Place the yeast and warm water in a large bowl and stir with a fork to dissolve the yeast. Let stand for about 3 minutes.
Whisk the whole wheat flour, unbleached flour, oats, and salt together in a medium bowl.
Add the sponge starter, cool water, honey, molasses, and oil to the yeast mixture. Mix with your fingers for 1 to 2 minutes, just long enough to break up the sponge (the mixture should look milky and be slightly foamy). Add the flour mixture to the bowl and stir with your fingers to incorporate the flour, scraping the sides of the bowl and folding the dough over itself until it gathers into a shaggy mass. Don't be concerned if the dough feels very sticky at this point.
Lightly flour a work surface. Remove the dough from the bowl and knead it for 6 to 8 minutes, until it becomes compact and elastic. It should be very moist but not mushy. If it feels too stiff to knead, add water 1 tablespoon at a time until you have a soft, malleable dough. If it's sloppy wet and impossible to knead, add another 1/4 to 1/3 cup (1 1/4 to 1 2/3 ounces) of whole wheat flour. Shape the dough into a loose ball and let it rest, covered with plastic wrap, on the lightly floured work surface for 20 minutes. (This rest period is the autolyse.)
Flatten the dough and stretch it gently into a rectangle about an inch thick. Spread the pecans and raisins evenly over the dough. Fold the whole mass into an envelope and knead and fold it gently until the nuts are well distributed, about 2 to 3 minutes. If the dough resists, let it rest for 5 minutes and then continue kneading. Some of the nuts may pop out of the dough, but they can easily be incorporated again after the first rise, when the dough has softened.
Shape the dough into a loose ball and place it in a lightly oiled bowl, along with any loose nuts. Turn the dough to coat the top with oil, and cover the bowl tightly with plastic wrap. Let the dough rise at room temperature (75 to 77 degrees F) until it has doubled in volume, about 2 1/2 to 3 hours. (You can also refrigerate this dough overnight and shape it and bake it the next day: Let it rise for 1 hour at room temperature, or until it looks slightly puffy but not doubled, before refrigerating. The next day, let it rise for 2 hours at room temperature before shaping it.)
When the dough has doubled, loosen it from the bowl with lightly floured hands and gently pour it onto a floured work surface. Press any loose pecans into the dough and divide it into 2 equal pieces. Shape each piece into a log. Spread the oats for topping on a flat plate or baking sheet. Use a pastry brush or a plant sprayer to lightly moisten the top of each log with water, then roll the tops of the loaves in the oats. Place each loaf seam side down in an oiled 9 by 5-inch loaf pan. Cover them with plastic wrap and allow to rise for about 2 hours, or until they have doubled in size (a finger pressed into the dough will leave an indentation).
Thirty minutes before baking, preheat the oven to 425 degrees F. Place a baking stone in the oven to preheat and place an empty water pan directly below the stone.
When the loaves have doubled, place the pans on the baking stone. Quickly pour 1 cup of very hot water into the water pan and immediately shut the door. After 1 minute, using a plant sprayer, mist the loaves quickly 6 to 8 times then shut the oven door. Repeat the misting procedure 1 minute later.
Bake for 15 minutes, then reduce the oven temperature to 375 degrees F and bake for 20 to 25 minutes longer, until the loaves sound slightly hollow when tipped out of the pan and tapped on the bottom. The sides and bottom of the loaf should feel firm and slightly crusty. If the tops are browned but the sides are still somewhat soft, place the loaves directly on the stone to bake for 5 to 10 minutes longer. Transfer the loaves from the pans to a rack and allow to cool completely before slicing.
Recipe courtesy of Amy Scherber