In a small heatproof bowl, combine flax seeds, sunflower seeds, chia seeds, and boiling water. Stir well, then cover and let sit for at least 15 minutes, or until the water is absorbed and the mixture is gelatinous. This can be prepared up to an hour in advance.

In the bowl of a stand mixer, combine the warm water, honey (or maple syrup), and instant dry yeast. Stir gently and let sit for 5-10 minutes until foamy, indicating the yeast is active.

Add the bread flour, whole wheat flour, rye flour, rolled oats, and sea salt to the yeast mixture in the stand mixer. Add the olive oil and the prepared seed soak.

Attach the dough hook to the stand mixer. Mix on low speed for 2-3 minutes until all ingredients are well combined and a shaggy dough forms. Scrape down the sides of the bowl as needed.

Increase the speed to medium-low and knead for 8-10 minutes, or until the dough is smooth, elastic, and pulls away cleanly from the sides of the bowl. It should be slightly tacky but not sticky.

Lightly grease a large clean bowl with olive oil. Transfer the dough to the greased bowl, turning once to coat. Cover the bowl tightly with plastic wrap or a clean kitchen towel.

Place the bowl in a warm, draft-free place (such as a turned-off oven with the light on) and let rise for 90-120 minutes, or until doubled in size. The exact time will depend on the temperature of your kitchen.

Gently punch down the dough to release the air. Transfer the dough to a lightly floured work surface.

Shape the dough into a round boule or an oblong batard. To do this, gently flatten the dough into a rough rectangle, then fold the top third down to the center, and the bottom third up and over to meet the top. Pinch the seam. Then, roll it tightly from one end to the other to create tension on the surface. Pinch the seams closed at the bottom.

If using a Dutch oven, line the bottom of a proofing basket (banneton) or a bowl with parchment paper, leaving generous overhang. If using a baking sheet, place the shaped loaf directly onto a piece of parchment paper on a baking sheet. Sprinkle the top of the loaf with the optional rolled oats, sesame seeds, and poppy seeds.

Cover the loaf loosely with a clean kitchen towel or plastic wrap. Let it rise in a warm place for 45-60 minutes, or until it looks puffy and springs back slowly when gently poked (do not let it overproof).

About 30 minutes before baking, preheat your oven to 450°F (232°C) with the Dutch oven (if using) inside. If using a baking sheet, just preheat the oven.

Carefully remove the hot Dutch oven from the oven. Using the parchment paper, gently transfer the proofed dough into the hot Dutch oven (or onto the preheated baking sheet). Using a sharp knife or a bread lame, score the top of the loaf with a single deep slash or a decorative pattern.

If using a Dutch oven, cover it with its lid and return it to the oven. Bake for 25 minutes covered.

Remove the lid (or continue baking if using a baking sheet) and reduce the oven temperature to 425°F (218°C). Bake for another 15-20 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210°F (93-99°C).

Carefully remove the bread from the Dutch oven or baking sheet and transfer it to a wire cooling rack. Allow the bread to cool completely for at least 1-2 hours before slicing. Slicing too early can result in a gummy texture.