In a large mixing bowl, combine the whole wheat flour, instant yeast, and salt. Whisk briefly to ensure everything is evenly distributed.

Pour the warm water into the dry ingredients. Using a wooden spoon or a spatula, mix until a shaggy, sticky dough forms and all the flour is incorporated. Do not overmix; just ensure there are no dry spots.

Cover the bowl tightly with plastic wrap or a damp kitchen towel. Let the dough rest at room temperature (ideally 68-72°F / 20-22°C) for 12 to 18 hours. The dough should double in size, be bubbly, and have a strong yeast smell.

Lightly flour your work surface. Gently scrape the dough out of the bowl onto the floured surface. Fold the edges of the dough towards the center a few times to create a round or oval shape. Avoid deflating it too much. If the dough is very sticky, dust your hands with a little flour. Place the shaped dough, seam-side down, onto a piece of parchment paper. This will make transferring it to the hot Dutch oven much easier.

Cover the dough loosely with plastic wrap or a kitchen towel and let it rest for another 20-30 minutes while you preheat the oven. The dough will puff up slightly during this time.

About 20 minutes into the second rise, place your Dutch oven with its lid into the cold oven. Preheat the oven to 450°F (232°C). Allow the Dutch oven to heat thoroughly for at least 30 minutes.

Carefully remove the hot Dutch oven from the oven. Lift the dough by the parchment paper and gently lower it into the hot Dutch oven. Score the top of the dough once or twice with a sharp knife if desired. Place the lid back on the Dutch oven and bake for 30 minutes.

Remove the lid from the Dutch oven and continue baking for another 20-25 minutes, or until the crust is deep golden brown and the internal temperature reaches 200-210°F (93-99°C).

Carefully remove the bread from the Dutch oven and transfer it to a wire rack to cool completely before slicing, at least 1-2 hours. Slicing too early will result in a gummy texture.