Mix Dry Ingredients: In a large mixing bowl, combine the all-purpose flour, bread flour, salt, and active dry yeast.
Add Wet Ingredients: Slowly pour in the warm water, stirring with a wooden spoon until the dough starts to come together. The dough will be sticky but manageable. Add Flavorings: Fold in the lemon zest and fresh thyme leaves until evenly distributed throughout the dough.
Knead the Dough: On a lightly floured surface, knead the dough for 5-7 minutes, until it becomes smooth and elastic. If the dough is too sticky, add a small amount of flour as needed. First Rise: Transfer the dough to a lightly oiled bowl, cover with a clean kitchen towel, and let it rise for 1-1.5 hours in a warm, draft-free spot, or until it doubles in size.
Shape the Dough: Punch down the dough and turn it out onto a floured surface. Shape it into a round loaf by folding the edges toward the center and flipping it over to create a smooth top. Second Rise: Let the dough rest for about 20 minutes while you preheat your Dutch oven.
Preheat Dutch Oven: Place your Dutch oven with its lid in the oven and preheat to 450°F (232°C) for 30 minutes.
Bake the Bread: Carefully remove the Dutch oven from the oven and place a piece of parchment paper inside.Gently transfer the dough onto the parchment paper and place it into the hot Dutch oven. Cover with the lid and bake for 30 minutes. Remove the lid and bake for an additional 10-15 minutes, until the top is golden brown and the bread sounds hollow when tapped on the bottom. Cool: Remove the bread from the oven and allow it to cool on a wire rack for at least 20 minutes before slicing.