In a large mixing bowl, combine the bread flour, wheat bran or oat bran, salt, instant yeast, and water. Stir the mixture with a wooden spoon until the ingredients are well incorporated. Allow the dough to rest at room temperature for about 2 hours, or until you notice some foaming on the surface, indicating that the yeast is active.
Cover the mixing bowl and place it in the refrigerator. Let the dough rest there for 24-48 hours. During this time, it will rise and develop a spiderweb-like texture on the surface.
When you're ready to bake, preheat your oven to 450°F and place a Dutch oven inside to heat up as well. Be cautious when removing the hot pot from the oven.
While the oven and pot are preheating, sprinkle cornmeal or flour on a sheet of parchment paper and place the dough on it. Lightly dust your hands with flour and gently shape the risen dough into a ball. Be sure to handle the dough as little as possible. Cut a few slits on the surface of the dough, then carefully transfer it to the Dutch oven.
Cover the Dutch oven with its lid and place it in the preheated oven to bake for 30 minutes. Afterward, take off the lid and continue baking for another 10-15 minutes, or until the bread turns golden brown.
When the bread is finished baking, carefully take it out of the oven and place it on a wire rack. Allow it to cool for at least 30 minutes before slicing and serving. Enjoy your delicious no-knead bran bread!