Smoked Sausage Pizza

Set oven rack in lowest position; preheat oven to 500°F (or the highest setting). Sprinkle a pizza pan or baking sheet generously with cornmeal; set aside. Roll dough on a lightly floured surface into a 14-inch circle or a 15-by-10-inch rectangle. Transfer the dough to the prepared pan. Spread marinara sauce evenly over the dough. Scatter onion, bell pepper, sausage and cheese over the top and sprinkle with oregano and red-pepper flakes (if using). Sprinkle with salt and pepper. Bake the pizza until the bottom and edges are browned, 12 to 15 minutes. Slice and serve.