In a small bowl, proof the yeast by dissolving it in ½ cup of the lukewarm water with 1 teaspoon (5 ml / 0.2 fl oz) of granulated sugar.
Let it stand for about 10 minutes until it becomes foamy and bubbly.
While the yeast proofs, place the raisins in a bowl and cover them with boiling water.
Let them sit for 10 minutes to plump up, then drain them thoroughly.
In a saucepan, gently heat the 1 cup (240 ml) of milk and the remaining 1 cup (240 ml) of water until lukewarm.
In a large mixing bowl, combine this warm milk-water mixture with the proofed yeast, brown sugar, plumped raisins, orange zest, and crushed fennel seeds.
Add 2 cups (480 ml) of the rye flour and beat with a wooden spoon until the batter is smooth.
Stir in the melted butter and salt.
Gradually add the remaining 2 ½ cups of rye flour, about ½ cup at a time, followed by 1 cup (240 ml) of the all-purpose flour.
Continue mixing until the dough becomes too stiff to stir with a spoon.
Generously flour a clean work surface with 1 cup (240 ml) of the all-purpose flour and turn the sticky dough out onto it.
Sprinkle the remaining flour over the top. Begin to knead the dough, using the flour on the board to prevent sticking.
Knead for 15-20 minutes, adding only as much extra flour as needed, until the dough is smooth and elastic.
Form the dough into a ball and place it in a large, well-buttered bowl, turning it over to coat the entire surface with butter.
Cover the bowl with a tea towel and let it rise in a warm, draft-free place for 1 hour, or until it has doubled in size.
Gently punch down the risen dough. Give it a few quick kneads on a lightly floured surface, then divide it in half.
Shape each half into a smooth, round loaf, pinching the seams together firmly at the bottom.
Butter two baking sheets and sprinkle them with cornmeal.
Place one loaf on each sheet, seam-side down.
Using a sharp, serrated knife, score a large 'X' into the top of each loaf.
Cover with a tea towel and let them rise for a final 1 hour, or until they have nearly doubled in size.
Towards the end of the second rise, preheat your oven to 375°F (190°C). Just before baking, brush the tops of the loaves with water.
Bake for 1 hour, or until the loaves are deep golden brown and sound hollow when tapped on the bottom.
Transfer the hot loaves to a wire rack to cool completely before slicing. This is crucial for the texture, so be patient!
