Chef John's Whole Wheat Ciabatta

Ingredients (13)

• + 1 cup warm water add to pantry
• + ½ cup all-purpose flour add to pantry
• + ½ cup whole wheat flour add to pantry
• + ¼ cup rye flour add to pantry
• + ¼ teaspoon active dry yeast add to pantry
• ✓ ½ cup water at room temperature
• + 2 tablespoons shelled sunflower seeds add to pantry
• + 1 tablespoon polenta add to pantry
• + 1 tablespoon ground flax seeds add to pantry
• ✓ 1 ¾ teaspoons salt
• + 1 ½ teaspoons honey add to pantry
• ✓ ½ teaspoon cornmeal, or as needed
• + water as needed add to pantry