Combine the flours and water in a large bowl. Use a wooden spoon or a Danish dough whisk to combine thoroughly until no dry patches of flour remain. Cover with a clean kitchen towel or plastic wrap, and let rest at room temperature for 30 minutes.

Add the salt and dry active yeast, and use your fingers to pinch in until fully incorporated. Cover and let rest at room temperature for 30 minutes.

Stretch and fold the dough in the bowl. Gently lift and stretch one edge of the dough up and lay it over itself. Be careful not to stretch too far, you don't want to tear the dough. Work your way around the perimeter of the dough, until each side has been stretched. Cover the bowl, and let rest for another 30 minutes. Then, repeat the stretch and fold process again. Cover the bowl, and let bulk ferment (rise) at room temperature for 18 hours.

After 18 hours, the dough should look puffy and have bubbles on the surface. Spray a 9x5" loaf pan with nonstick cooking spray, or line with parchment paper. Pour the dough out onto a lightly floured surface.

Preshape the dough by gently stretching it into a rectangle shape, and fold the long edges into the center. Let the dough rest for 5 minutes, uncovered. Then roll the dough up into a long log shape, and place it seam side down into the prepared loaf pan., sprinkle the top lightly with flour and cover with a clean kitchen towel. Allow to proof at room temperature for 1.5 hours until puffy.

Meanwhile preheat the oven to 450°F. Just before baking, place a baking pan filled with ice cubes on the bottom rack of the oven. This will create steam inside the oven, and allow the bread to rise to it's fullest potential. Additionally, you can spray water directly into the hot oven and onto the surface of the bread as it goes into the oven.

Bake the bread for 30-35 minutes until deeply golden brown. IMPORTANT: allow the bread to cool completely before slicing into it. Enjoy!