Mix together flour, sourdough start, water, honey, and salt in the bowl of a stand mixer. Stir until just combined and then let sit for 15 to 30 minutes.
Add the flax seeds, sunflower seeds, poppy seeds, and dried fruit.
Using a dough hook, knead for 5 minutes. If making by hand, knead for 8 to 10 minutes. Adjust flour and water as needed to create a dough that's still clinging to the bottom of the bowl, but also clearing the upper part of the bowl. It should be tacky, but not cling to your finger.
Transfer to a medium-sized bowl, lightly coated with oil. Cover with towel and let rise for 3 hours, turning and folding four times.
Remove the dough, turn and fold again, gently shaping the dough into a round or oval shape and place it in a floured banatan bowl or regular bowl seam-side up. Let rise for another 2 hours.
Set an enameled, cast iron dutch oven into a cold oven and turn heat to 450 degrees and pre heat for 1 hour.
While oven is pre heating and after second rise, place a square of parchment on the counter. Dump the bread out of the bowl onto the parchment paper seam-side down. Take one egg breaking it into a small bowl whisking to create an egg wash. Brush just the top of the bread with the egg wash and sprinkle with additional flax seeds and sunflower seeds. If you have them, pumpkin seeds work well too.
When the oven is ready, slash the top of the loaf with a razor blade or serrated knife and transfer it to the hot pot by holding the edges of the parchment to gently lower into the pot. The bread will bake while on the parchment.
Replace the hot lid and bake for 20 minutes. Remove the lid and continue to bake for another 20 minutes until golden brown.
Remove to a wire rack to cool at least 1 hour before cutting.