1. Combine the bulgur, polenta, millet, and quinoa in a large bowl. Add the boiling water and stir. Let stand, stirring often, for about 20 minutes.
2. Add the milk and honey to the cooled grain mixture, along with the cold water, the oil, and salt. Stir in the bread flour, oats, rye flakes, and yeast.
3. Stir in enough of the whole wheat flour to make a heavy and sticky dough that is difficult to stir. Dust the work surface with whole wheat flour and turn out the dough. Knead for 5 minutes, adding more flour as necessary (whole grain dough will remain a little sticky). Add the cooked rice, if using, and knead 5 minutes more or until the dough is supple and tacky.
4. Coat the inside of a bowl with oil. Shape the dough into a ball, place in the bowl, and turn to coat with oil. Cover the bowl with plastic wrap. Let stand in a warm place about 1 hour, or until the dough doubles in volume.
5. Lightly oil two 9 × 5in (23 x13cm) loaf pans. Knead the dough on the floured work surface for 1 minute. Cut the dough into 2 pieces and form each into a ball. Working with one ball at a time, use a floured rolling pin to roll the dough into a 9in x10in (23cm × 26cm) rectangle. Starting at a short side, roll up the dough, and pinch the long seam to seal. Place, seam side down, in the pan, and press to fill the pan with dough. Cover with a clean kitchen towel. Let rise in a warm place about 30 minutes, or until the dough reaches the tops of the pans.
6. Preheat the oven to 425°F (220°C). Gently brush the tops of the loaves with oil. Bake for 10 minutes. Reduce the heat to 375°F (190°C) and continue baking for 25 to 30 minutes or until the unmolded loaves sound hollow when tapped on the bottom. Cool briefly, then remove the loaves from the pans and cool completely on wire racks.
Seven Grain Rolls: Cut the risen dough into rolls and follow the rest of step 5. Bake for 20 minutes or until they sound hollow when tapped on the base.