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 olive oil. Stir with a wooden spoon until a sticky, cohesive dough forms.
02 - Knead the dough gently directly in the bowl for 1 to 2 minutes. 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 the dough has 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 - Coat a large baking sheet (approximately 12x16 inches) generously with olive oil. Turn the risen dough onto the prepared sheet. Using oiled fingertips, gently stretch and press the dough toward the edges. If the dough resists, let it rest for 15 minutes before continuing to stretch.
05 - Preheat the oven to 425°F, ensuring the rack is positioned in the center.
06 - Press dimples into 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 par-baked focaccia from the oven. Spread the prepared pizza sauce evenly across the surface. Scatter the shredded mozzarella over the sauce, then arrange the pepperoni (if using), sliced bell peppers, red onion, black olives, and mushrooms on top. Finish with freshly ground black pepper.
08 - Return the assembled focaccia pizza to the oven and bake for an additional 15 minutes, or until the cheese is fully melted and bubbly and the crust edges are golden brown.
09 - Allow the focaccia pizza to stand for 5 minutes after removing from the oven. Sprinkle with chopped fresh basil, slice into squares, and serve warm.