Whisk together honey or maple syrup and water. Sprinkle yeast across the top and let sit for 10-15 minutes.
In a large bowl, whisk together flour, oats, pumpkin seeds, sunflower seeds, ground flaxseed, sesame seeds and salt. Let sit for 10 minutes.
Add yeast mixture to the bowl and use a rubber spatula to mix just until combined. If you find the dough to be too dry, add a little more water a teaspoon at a time (usually 1 teaspoon is enough, two at most). The dough should be thick and look a little shaggy and there should still be a little flour around the edges of the bowl.
Cover and let rise somewhere warm (see note below) until it has doubled in size, about 8-10 hours.
Once the dough has doubled in volume, use your hands (or a dough scraper if you have one) to pull the dough out onto a floured surface. With floured hands, gently fold the dough into itself several times until a soft, flour-covered ball is formed. Seam side up, lift and place it into a flour dusted proofing bowl like this one. Dust with flour, cover and refrigerate for a minimum of 1 hour or as long as 24 hours. You can even leave it for as long as 48 hours at this point if you’re not able to bake it right away.
When you're ready to bake your bread, preheat oven to 425ºF (220ºC) with a Dutch oven or covered baking vessel inside the oven.
Uncover then invert the bowl to turn the dough out onto parchment paper seam side down. If needed, gently turn it with your hands and nudge it into the shape of a loaf. Brush dough lightly with a little filtered water and sprinkle remaining oats and seeds across the surface of your loaf, pressing them into the dough as you go so they hold. Score the top with a razor blade or the tip of a sharp knife with a design of your choosing. This will allow steam to escape while it’s baking.
Once the oven is preheated, remove the Dutch oven from the oven and transfer the dough, still on the parchment, into the Dutch oven. Cover and bake for 40 minutes, then remove the cover and bake for 15-20 minutes more. Your bread will be done once the top is browned, and it sounds hollow when you tap the top.
Using parchment edges, lift bread from Dutch oven and transfer it to a wire cooling rack to let cool for up to an hour before slicing.