Mix dry ingredients: Combine flour, sunflower seeds, pumpkin seeds, sesame seeds, salt, and instant yeast in large bowl. Stir well to distribute evenly.
Add water: Pour warm water (and honey if using) into flour mixture. Stir with wooden spoon until all flour is incorporated and you have shaggy, sticky dough. Don't knead.
First rise: Cover bowl tightly with plastic wrap or damp towel. Let rise at room temperature 12-18 hours until doubled and bubbly on surface.
Shape dough: Generously flour work surface and hands. Turn out bubbly dough. With floured hands, fold dough over itself 8-10 times from edges to center. Don't knead.
Form loaf: Shape into rough ball by tucking edges underneath. Place seam-side down on parchment paper. Cover loosely and let rest 1-2 hours until puffy.
Preheat Dutch oven: 30 minutes before second rise ends, place Dutch oven with lid in oven. Preheat to 450°F.
Score bread: Brush dough lightly with water and sprinkle with reserved seeds. Make 2-3 slashes ½ inch deep across top with sharp knife.
Bake covered: Using parchment as sling, lower dough into hot Dutch oven. Cover with lid. Bake 30 minutes covered.
Finish baking: Remove lid. Bake uncovered 12-15 minutes more until deep golden brown and internal temp reaches 200-210°F.
Cool completely: Remove bread to wire rack. Cool completely, at least 1 hour (preferably 2), before slicing.