1. In a large bowl, whisk together 4 cups bread flour and 2¼ teaspoons active dry yeast (or ¾ ounce fresh yeast). Add 1⅔ cups warm water (about 100°F) and stir until the dough just comes together with no dry flour remaining.
2. Cover the bowl and let it rest for 15 minutes so the flour can fully hydrate.
3. Add 1¾ teaspoons fine salt and 3 tablespoons extra-virgin olive oil. Using stretching and folding motions, knead the dough in the bowl for 5 to 7 minutes until it’s smooth and elastic.
4. Lightly oil a clean bowl with olive oil and transfer the dough to it, turning to coat all sides. Cover and let it rise in a warm spot for 1½ to 2 hours, or until doubled in size.
5. Drizzle a rimmed baking sheet (about 12×16 inches) with olive oil. Transfer the dough to the pan without deflating it, then use your fingertips to gently stretch it out and make dimples all over the surface.
6. Drizzle the top with a little more olive oil, then scatter fresh rosemary sprigs, pitted black olives, and halved cherry tomatoes over the dough. Sprinkle with flaky sea salt. Let it rise for another 30 to 45 minutes, until puffy.
7. Meanwhile, preheat the oven to 425°F.
8. Bake the focaccia for 20 to 25 minutes, or until the edges are golden brown and crisp.
9. Remove the focaccia from the oven, drizzle with a little extra olive oil, and let it rest on a wire rack for a few minutes before slicing and serving.