01 - In a large mixing bowl, combine the flour, instant yeast, and fine sea salt. Pour in the warm water and 3 1/2 tablespoons of extra-virgin olive oil. Stir with a wooden spoon until a sticky, shaggy dough comes together.
02 - Knead the dough gently directly in the bowl for 1 to 2 minutes until it becomes smoother. Cover tightly with plastic wrap or a damp kitchen towel. Place in a warm, draft-free spot and let rise for 1 to 2 hours, or until doubled in volume.
03 - While the dough rises, heat 1 tablespoon of olive oil in a small saucepan over medium heat. Sauté the minced garlic until fragrant, about 30 seconds. Stir in the passata, dried oregano, salt, and sugar. Simmer gently for 10 minutes, stirring occasionally, then set aside to cool.
04 - Generously coat a large baking sheet (approximately 12x16 inches) with olive oil. Turn the risen dough out onto the prepared sheet. Using oiled fingers, gently press and stretch the dough toward the edges. If the dough springs back, let it rest for 15 minutes before continuing to stretch.
05 - Preheat the oven to 425°F, positioning the rack in the center of the oven.
06 - Press deep dimples across the surface of the dough using your fingertips. Drizzle lightly with additional olive oil. Pre-bake for 10 minutes until the dough is just set but not yet browned.
07 - Remove the partially baked focaccia from the oven. Spread the pizza sauce evenly across the surface. Layer on the shredded mozzarella, then arrange the pepperoni (if using), sliced red and green bell peppers, red onion, black olives, and mushrooms. Finish with a generous crack of black pepper.
08 - Return the focaccia to the oven and bake for an additional 15 minutes, or until the cheese is fully melted and bubbly and the crust edges are deeply golden.
09 - Allow the focaccia to stand for 5 minutes before slicing. Sprinkle with chopped fresh basil, cut into portions, and serve warm.