Oil baking sheet with 2 Tbsp of olive oil and gently stretch the dough to fit, making sure not to pop too many air bubbles. Drizzle with the remaining 1 tablespoon olive oil and cover. Allow to rise until it fills the pan, about 1 hour and 30 minutes.
Preheat the oven to 425°F. Position oneoven rack as low to the bottom of the oven as possible and the other at the very top.
Spread the tomato-onion sauce evenly over the top. Sprinkle with the cheese, oregano and seasoned salt.
Bake on the top rack for 10 minutes, then move the pan to the upper third and bake another 10 minutes.
Cool for 10 minutes in the pan, then using a thin spatula, remove the bread from the pan to cool completely on a wire rack. Slice into thick squares, and serve warm.