In a large bowl, whisk together flour, salt, pepper, and instant yeast. Stir in the garlic and rosemary until well combined.
Pour in 1½ cups of lukewarm water. Stir with a wooden spoon until a shaggy, sticky dough forms. Cover with plastic wrap or a damp towel and let it rest for 5 minutes.
Leave the dough at room temperature for 12–18 hours. It should become puffy, bubbly, and slightly sticky with air pockets on the surface.
Lightly flour a surface and turn the dough out. Dust the top with a little flour. Gently fold it a few times and shape into a round or oval loaf without overworking.
Place the dough on parchment paper or in a floured proofing basket. Cover and let rise for 2–3 hours, until doubled. Preheat the oven to 450°F (230°C) during the last hour. If using a Dutch oven, preheat that too.
Carefully transfer the dough (with parchment) into the hot Dutch oven. Score the top with a sharp knife. Bake for 30–35 minutes until the crust is deep golden and sounds hollow when tapped.
Move the loaf to a wire rack and let it cool completely before slicing. This keeps the crumb from turning gummy.