Combine flour, oats, brown sugar, seeds, salt and yeast in a large bowl. Stir well to combine. Make a well in the center of the flour mixture.
Add about ¾ of the hot water and stir with a rubber spatula, scraping the sides of the bowl, then bringing the mixture to the center. Rotate the bowl as you stir. When the mixture gets difficult to stir, add more of the water in increments, stirring as you go until all of the water is added and all of the flour mixture is well-incorporated. The dough should be thick, but a little shaggy. If it still seems a little dry and all of the flour is not mixed in, add another tablespoon of hot tap water, one teaspoon at a time.
Cover the bowl tightly with plastic wrap and allow to sit at room temperature for one hour then refrigerate for at least eight hours and up to 48 hours.
Place a piece of parchment paper on a work surface and sprinkle it with about 2 teaspoons of flour. Set aside.
Sprinkle about 1 tablespoon of flour onto a work surface (counter). Transfer the dough from the bowl with a spatula to the prepared surface. Sprinkle the top of the dough lightly with a little more flour.
Gently press dough just to level and even it out a bit. Then, starting on one side and turning the dough as you go, fold the edges of dough toward center, pressing lightly in the center. Now turn the dough ball over, and using both hands, cup dough around the edges to form a smooth, tight ball. Place the dough onto the prepared sheet pan and cover it with a clean kitchen towel. Allow the dough to rise for 20 minutes.
After 20 minutes of rising time, place a 5-7 quart Dutch oven on the center rack in the oven. Turn the oven to 425℉ and allow it to preheat for 30-40 minutes. The dough will be puffing up at this point, but will not have doubled in size.
Brush half of the top of the loaf with water, and sprinkle with the seeded topping. Cup one hand along the bottom edges as you sprinkle the seeds catching the excess in your hand, then gently press the extra seeds onto the side of the loaf. Once half of the loaf is sprinkled with seeds, brush the other half with water and repeat the sprinkling and pressing process. Don’t worry if some seeds are on the parchment paper.
Remove the Dutch oven (it's hot!) and place on the stovetop. Place the sheet pan with the dough next to the Dutch oven. Pick up the dough ball by the parchment paper and lower it into the Dutch oven. Be careful as the pot will be very hot. Cover the Dutch oven and return it to the oven.
Bake for 40 minutes, covered then remove the cover and bake for another 5-20 minutes or until the bread is a nice golden color. (Check it every 5 minutes at this point.)
Remove the Dutch oven from the oven and lift the bread, using the parchment paper onto a cooling rack. Gently slide the parchment paper (and excess seeds) away from the bottom of the loaf and discard.
IMPORTANT - Allow the bread to cool completely before slicing.