Combine the Rye Mixture: In a large mixing bowl, stir together the rye flour, instant yeast, molasses, and lukewarm water until you have a very wet, loose mixture with no visible pockets of dry flour.
Rest the Rye Mixture: Set the mixture aside for 20 minutes so the rye flour can absorb some of the liquid.
Form the Dough: Add the all-purpose flour, whole wheat flour, salt, and the optional caraway, coriander, and fennel seeds. Mix everything in the bowl for a few minutes until a wet dough forms and no dry flour remains visible. Knead the Dough: Turn the dough onto a generously floured work surface and knead for 5–10 minutes, working it until it becomes a smooth ball. If the dough remains very sticky, periodically sprinkle in about 1 teaspoon of all-purpose flour or rye flour as needed. First Rise: Lightly coat a clean mixing bowl with olive oil and place the kneaded dough inside. Cover the bowl with a clean kitchen towel and leave the dough in a warm spot until it has approximately doubled in size, about 1 hour.
Shape the Loaf: Turn the risen dough onto a lightly floured work surface. Shape it into a round or oval loaf, gently bringing the top edges down along the sides and underneath to create surface tension. Tuck all seams and edges underneath the loaf.
Prepare for Proofing: Transfer the shaped dough to a baking sheet lined with parchment paper or a silicone baking mat. Lightly dust the surface with a little flour to prevent the towel from sticking.
Second Proof: Cover the shaped loaf with a clean towel and let it proof for another 1 hour in a warm, draft-free place. The loaf is ready when it has visibly puffed up; it may not completely double in size.
Preheat the Oven: Preheat the oven to 400°F before baking the loaf.
Bake the Bread: Bake the loaf for 30–35 minutes, until the crust is crisp and the bottom of the loaf sounds hollow when tapped.
Cool Before Slicing: Transfer the baked bread to a cooling rack and allow it to cool for at least 30 minutes before slicing.
