01 - In a large mixing bowl, whisk together the flour, instant yeast, sugar, and salt. Pour in the warm water and olive oil, stirring until a slightly sticky dough forms.
02 - Turn the dough onto a lightly floured surface and knead for 5 to 8 minutes until smooth and elastic. Place the dough in an oiled bowl, cover with a damp towel or plastic wrap, and let it rise in a warm spot until doubled in size, about 1 hour.
03 - Preheat the oven to 430°F. Generously oil a 9x13-inch baking pan with olive oil.
04 - Stretch the risen dough into the prepared pan, using your fingertips to press and dimple the surface evenly. Drizzle generously with olive oil and let the dough rest for another 20 minutes to puff slightly.
05 - Spread the pizza sauce evenly over the dough. Layer on the shredded mozzarella, pepperoni slices, crumbled Italian sausage, sliced red onion, green bell pepper strips, and black olives. Finish with a generous sprinkling of Parmesan cheese and dried oregano.
06 - Bake on the center rack for 20 to 25 minutes, until the crust is golden brown and the cheese is melted and bubbly.
07 - Remove from the oven and let the focaccia pizza cool for 5 minutes. Scatter fresh basil leaves over the top, slice into squares, and serve warm.