Step 1

In a stand mixer with the paddle attachment, mix the corn flour, honey and boiling water on low until evenly moistened and a thick mash forms, 30 to 60 seconds. Turn off the mixer and let sit until just warm to the touch, about 30 minutes. Meanwhile, line a rimmed baking sheet with kitchen parchment.

Step 2

Add the room-temperature water, bread and rye flours, yeast and salt. Using the dough hook attachment, mix on low, scraping down the bowl as needed, until a cohesive dough forms, about 5 minutes; the dough should clear the sides of the bowl and feel tacky but not excessively sticky.

Step 3

Turn it out onto the counter and use your hands to shape the dough into a ball about 5 inches in diameter. Set on the prepared baking sheet, dust the top with flour and cover with a kitchen towel. Let rise in a warm, draft-free spot until the volume increases by about 50 percent, 1 to 1½ hours.Meanwhile, heat the oven to 500°F with a rack in the middle position.

Step 4

Bake the bread for 15 minutes. Reduce to 300°F and continue to bake until deep golden brown, another 30 to 35 minutes. Transfer the bread from the baking sheet to a wire rack and let cool completely, about 2 hours.