How to Make It
MAKE THE SPONGE: In a large bowl, mix the whole wheat flour with the water and yeast until blended. Cover and let stand overnight at room temperature.
MAKE THE BREAD: In a medium saucepan, cover the rye berries with the water, add a large pinch of salt and bring to a boil. Cover and simmer over low heat until the rye berries are tender, about 45 minutes. Drain and let cool to room temperature.
Add the rye berries to the sponge. Using a wooden spoon, stir in the rye flour, whole wheat flour, caraway seeds and 1 tablespoon plus 1 teaspoon of salt. When the dough becomes too stiff to mix, scrape it out onto a floured work surface. Using a dough scraper, lightly knead the dough, adding any leftover flour, until the dough forms a cohesive but sticky mass. Transfer the dough to a clean bowl. Cover and let stand in a cool place until the dough increases in volume by two-thirds and holds an impression when lightly pressed, about 2 hours.
Scrape the dough out onto a lightly floured surface. Using floured hands, briefly knead the dough. Cut it in half and shape each half into a 7-inch round. Sprinkle a large peel or rimless baking sheet generously with cornmeal. Transfer the loaves to the peel, leaving about 3 inches between them. Let stand in a cool place until the dough is well risen and holds a slight impression when lightly pressed, about 1 hour.
Set a pizza stone or baking tiles in the bottom shelf of the oven. Preheat the oven to 350° for 30 minutes. Slide the loaves onto the preheated stone or bake on the baking sheet for 30 minutes. Reduce the oven temperature to 325° and continue baking for about 45 minutes, or until the loaves are nicely risen and browned; they should sound hollow when tapped on the bottom. Transfer the loaves to a rack to cool for at least 4 hours before slicing.
Make Ahead: The bread can be refrigerated for up to 10 days.