Combine water (or whey), sugar, yeast, oats, rye flakes and wheat flakes in the work bowl of a stand mixer.
Combine quinoa and polenta in a saucepan. Add water to cover by 2". Cook over medium heat until quinoa is tender but not soft. Pour into fine-mesh strainer to drain and cool.
Meanwhile, add 1 c bread flour to mixer bowl and knead with dough hook about 5 minutes.
When quinoa and polenta have cooled to room temperature, add to the mixer bowl, along with remaining bread flour, white whole wheat flour, sesame seeds, salt, pumpkin seeds and 1 tbsp olive oil. Knead with dough hook until it forms a ball and cleans off the sides of the bowl, 5-7 minutes. If it doesn't clean up or form a ball, add more flour. It will still be wet and sticky.
Pour remaining 1/2 tbsp olive oil in a bowl. Form dough into a loose ball, and place in bowl; turn dough to coat all sides with oil. Cover bowl with plastic wrap and place in refrigerator for 2 hours.
Remove plastic, punch dough down and turn over on itself several times (i.e. perform 8 kneading turns). Recover with plastic wrap and return to the refrigerator overnight.
The next day, remove the bowl from the refrigerator and let stand at room temperature for 1 hour. Meanwhile, preheat oven (ideally, with a pizza stone) to 350°F Place a broiler tray or cast iron skillet on the lowest level (or floor) of your oven.
Knead the dough briefly and form into desired shape (boule, batard, baguette, couronne). Place on a bread peel (or cookie sheet, if you don't have a pizza stone) covered with cornmeal, cover loosely with plastic and let double in size, 45-60 minutes.
Slash loaf with a sharp blade. Slide bread onto pizza stone or place cookie sheet in oven. Pour 1 c hot water into broiler pan or skillet and quickly close oven door. Bake 50-60 minutes, until an instant read thermometer inserted into bottom of loaf reads 202-205°F and bread is brown and crisp.