Mix the bread flour and whole-wheat flour together in a large bowl.
Add water, yeast, and salt to the flour mixture.
Stir until a sticky dough forms.
Cover the bowl with plastic wrap and let the dough rest and rise for 12 to 18 hours at room temperature.
Shape the dough and let it rise for an additional 1 to 2 hours at room temperature.
Preheat a Dutch oven in the oven for 30 minutes at a high temperature.
Carefully transfer the dough into the hot Dutch oven.
Cover the Dutch oven with a lid and bake the bread for a specific time.
Remove the lid and continue baking for a few more minutes to brown the crust.
Let the bread cool completely before slicing and serving.
